Saudi Arabia's energy minister said that more than half of its daily crude oil production that was knocked out by a weekend attack had been restored.
Saudi Arabia said on Tuesday its oil output would be back to normal by the end of the month, with half the production lost in weekend attacks on two key facilities already restored.
Energy Minister Prince Abdulaziz bin Salman, who was only appointed to the role earlier this month, said that the world's top energy exporter had dipped into its strategic reserves to maintain supply to clients.
"I have good news for you... the oil output to international markets is back to what it was before the attack," he said.
"During the past two days the damage was contained and 50 percent of the production has been recovered," he added.
"Production will be back to normal by the end of September."
But as the US points the finger of blame at Saudi Arabia's regional rival Iran, the minister – the son of King Salman – refused to be drawn on who was responsible for the Saturday's strikes which roiled global energy markets.
"We don't know who is behind the attack," he said, adding that the kingdom wants "proof based on professionalism and internationally recognised standards".
Saudi authorities were also bullish on plans for the mega stock listing of oil giant Aramco, which was thought to be imperilled by the attack.
"The IPO will continue as is, we won't stop anything," said Aramco chairman Yasir al-Rumayyan.
Iran rules out talks with US
Iran's supreme leader ruled out talks with Washington after President Donald Trump blamed Tehran for the attack on Saudi Arabia's oil facilities.
Saudi King Salman called on governments around the world to confront the threats to oil supplies and global economic stability posed by the weekend attack. European allies said the crisis should be addressed collectively.
Trump said on Monday that it looked like Iran was behind the strike at the heart of the Saudi oil industry, which cut five percent of global production, but stressed he did not want to go to war. Iran denied it was to blame.
"Iranian officials, at any level, will never talk to American officials ... this is part of their policy to put pressure on Iran," Iranian state TV quoted Ayatollah Ali Khamenei as saying.
He said talks could only take place if the United States returned to a nuclear accord between Iran and the West that Trump abandoned last year.
US-Iran relations deteriorated after Trump quit the accord and reimposed sanctions over Tehran's nuclear and ballistic programmes. He also wants Iran to stop supporting regional proxies, including Yemen's Houthi group, which has claimed responsibility for the attack.
A day after warning that the United States was "locked and loaded" to respond to the incident, Trump said on Monday there was "no rush" to do so and that Washington was coordinating with Gulf Arab and European states.
"I'm not looking at options right now. We want to find definitively who did this."
Remember when Iran shot down a drone, saying knowingly that it was in their “airspace” when, in fact, it was nowhere close. They stuck strongly to that story knowing that it was a very big lie. Now they say that they had nothing to do with the attack on Saudi Arabia. We’ll see?— Donald J. Trump (@realDonaldTrump) September 16, 2019
US intel indicates attacks staged from Iran
American officials have shared intelligence with Riyadh indicating that Iran was the staging ground for the attacks on Saudi Arabia's oil installations, the Wall Street Journal reported.
While Washington has blamed Tehran, the Monday assessment on the origin of the attacks has not been shared publicly, the Journal said.
The US assessment determined that "Iran launched more than 20 drones and at least a dozen missiles," according to unnamed sources.
"But Saudi officials said the US didn't provide enough to conclude that the attack was launched from Iran, indicating the US information wasn't definitive," the WSJ added.
"US officials said they planned to share more information with the Saudis in the coming days."
Trump said he was sending Secretary of State Mike Pompeo to Saudi Arabia soon, but he had not made any commitments to protect the Saudis.
Riyadh asked international experts to join its investigation, which indicates the attack did not come from Yemen, the Foreign Ministry said. US officials say they believe it came from the opposite direction, possibly from Iran.
Iranian President Hassan Rouhani said Yemenis launched the strikes in retaliation for attacks by a Saudi-led coalition that has been battling the Houthis for four years. Riyadh says Tehran arms the group, which has fired missiles and drones on Saudi cities, a charge both deny.
The United Arab Emirates, a Saudi ally, rejected Rouhani's attempt to "justify the unprecedented terrorist attack."
"The attack on Saudi Arabia is a dangerous escalation in itself," senior Foreign Ministry official Anwar Gargash tweeted.
Tehran has warned that if it cannot export oil then neither can other producers. But it has denied involvement in earlier attacks on tankers in Gulf waters and Saudi energy assets.
Efforts by European countries
Britain and Germany agreed they needed to work with international partners to form a collective response and de-escalate tensions as efforts continued to establish exactly what happened, Prime Minister Boris Johnson's spokesman said.
German Chancellor Angela Merkel said the Iran nuclear pact, which European parties are trying to salvage, is one building block "we need to get back to."
Merkel also suggested she wanted to stick to Germany's halt in arms exports to Saudi despite the attacks, saying she did not see any reason to change the government's stance.
"At the moment I don't see any prerequisites for the government to change its position," Merkel told a news conference.
Saudi Arabia, which has supported tougher US sanctions on Iran, said an initial investigation showed the strikes were carried out with Iranian weapons. Despite the Houthi claim, the launch site was still being determined.
King Salman, heading a cabinet meeting on Monday, said Riyadh would handle the consequences of "cowardly attacks" that target vital Saudi installations, world crude supplies and global economic stability. The cabinet urged the world to confront those threats "regardless of their origin."
Worst attack in decades
The assault halved Saudi Arabia's oil output and damaged the world's biggest crude oil processing plant, triggering the largest jump in oil prices in decades. It was the worst such attack on regional oil facilities since Saddam Hussein torched Kuwait's oil wells during the 1990-91 Gulf War.
The Saudi energy minister will hold a news conference on Tuesday at 1715 GMT, giving what would be the first update since state oil giant Aramco announced on Sunday attacks on its plants in Abqaiq and Khurais had knocked out 5.7 million barrels per day.
Oil prices surged nearly 20 percent on Monday after the attack on the world's top oil exporter, which has been the supplier of last resort for decades. Prices fell after the United States said it would release US emergency supplies and producers said there were enough global stocks.
Riyadh said it would meet customers' demand from its ample storage. Aramco informed at least six refiners in Asia it would supply all allocated crude volumes in October.
Dollar-denominated bonds issued by the Saudi government and Aramco rebounded on Tuesday, in a sign investors' concern may be abating.
Aramco is preparing for an initial public offering, although some investors and analysts think it may be delayed as it has not said when oil output will be restored.