Largest opposition bloc says it has "not been summoned" to talks as US seeks to rebuild ties with South American oil giant amid surge in oil prices due to conflict in Ukraine.
Opposition parties have said they were not invited to new talks between US and Venezuela, whose Nicolas Maduro's government is not recognised by Washington.
"We have not been summoned (to the talks), we do not know the agenda," said Omar Barboza, a coordinator of the largest opposition bloc, told reporters on Tuesday.
On Monday, Maduro announced a US delegation had arrived in Venezuela to discuss a "bilateral agenda," expanding on talks in March the White House had said focused on American "energy security."
Maduro said that National Assembly speaker Jorge Rodriguez was hosting a US government delegation.
This was despite Venezuela being excluded this month from the Summit of the Americas hosted by US President Joe Biden in Los Angeles.
Rodriguez is also the government's negotiator in talks with the opposition that have been at a standstill since last October.
The United States and Venezuela severed diplomatic ties in 2019 after Maduro was re-elected in 2018 to a second term in a ballot boycotted by the opposition.
Before Washington enacted sanctions against Venezuela, the South American country exported almost all of its oil production to the United States.
Washington sent a high-level delegation to Caracas in March, just days after Russia began its "special military operation" in Ukraine.
Observers said the move sought to distance Caracas from ally Moscow and to discuss an easing of US sanctions on Venezuelan oil after Russia's incursion caused a spike in global fuel prices.
Thaw in ties
In a bid to oust Maduro from power after his disputed re-election, Washington and dozens of other countries recognised opposition leader Juan Guaido as interim president and imposed a battery of sanctions on Caracas.
These prevent Venezuela from trading its crude oil — which represented 96 percent of the country's income at the time — on the US market.
Since then, Maduro has received support from Russia to continue exporting oil despite the sanctions.
After the talks in March, Washington announced it would ease some sanctions against Venezuela, including one linked to the oil company Chevron, to promote dialogue between Maduro's government and the opposition.
Caracas also released two Americans detained in Venezuela in what was widely seen as a goodwill gesture.