Tamer al Kilani of the Lions' Den was killed when a bomb placed on a motorcycle parked nearby was detonated, according to the group.
Thousands joined the funeral procession of a senior member of a Palestinian group in the occupied West Bank city of Nablus.
The Lions’ Den said Tamer al Kilani was killed when a bomb placed on a nearby motorcycle exploded early on Sunday, blaming Israel for his death.
"The bomb exploded as he passed by and he became a martyr," said al Kilani's father, Sufian al Kilani, who was not at the scene when the bomb went off.
"We don't know whether the bomb was timed or triggered remotely."
There was no comment from the Israeli authorities on the death.
Israel blames the Palestinian group for a number of attacks against Israeli targets in the occupied West Bank.
READ MORE: Israeli troops kill Palestinian youth, wound three in West Bank
On October 12, the Lions’ Den group said it was responsible for a shooting attack in which an Israeli soldier was killed.
Tension has been running high across the occupied West Bank in recent weeks amid daily Israeli military raids in the occupied territory during which dozens of Palestinians were killed.
Thousands also bid farewell Rabi Arafah Rabi, 32, in the city of Qalqilya, according to an Anadolu Agency reporter at the scene.
Rabi died on Saturday from wounds he sustained from Israeli bullet to the head at a military checkpoint in the city, according to the health ministry.
More than 5,300 Palestinians detained
A Palestinian NGO has documented over 5,300 arrests by the Israeli army in the occupied West Bank so far this year.
In a statement, the Palestinian Prisoner Society said around 4,700 Palestinians are still in Israeli custody, including 30 women and 190 minors.
“The suffering of captives is escalating amid rising numbers of detainees in (Israeli) detention centers,” the statement said.
The United Nations said earlier this week that more than 100 Palestinian have been killed by Israeli fire since the start of the year, the heaviest toll in the occupied West Bank for nearly seven years.