Three masked men shot and killed a Hamas leader as he left a mosque in the West Bank on Wednesday, witnesses said, a day after a rival Palestinian faction threatened to kill senior Hamas members.
The shooting comes amid a growing power struggle between the ruling Hamas Islamist movement and the Fatah faction of President Mahmoud Abbas.
At least 12 people were killed and more than 100 wounded earlier this week in internal clashes.
Witnesses said the gunmen jumped out of a passing vehicle and shot Mohammed Odeh, 37, as he left the mosque after dawn prayers in Hableh, a village near the town of Qalqilya, and then sped off, the witnesses said.
They said the vehicle had Israeli licence plates but gave no other details. Vehicles with such plates are not uncommon in some major Palestinian cities in the occupied West Bank.
The Israeli military denied involvement in the shooting in the village, which lies northwest of the main West Bank city of Ramallah.
"We were not involved in any such incident near Qalqilya," an army spokesman said.
Odeh, described as a local leader of Hamas, died on the way to hospital, ambulance workers said.
The shooting occurred a day after an armed faction of Fatah threatened to kill senior Hamas leaders.
However, some witnesses suggested the gunmen could have been undercover Israeli agents.
Israel has carried out similar raids against militants in the West Bank in the past.
The violence this week in the Gaza Strip and the West Bank was the worst internal bloodshed since the Palestinian Authority was created in 1994.
Visiting the Middle East, US Secretary of State Condoleezza Rice urged an end to the fighting that has coincided with calls by Washington's Arab allies to restart Israeli-Palestinian peacemaking.
Rice is scheduled to meet Abbas in Ramallah later on Wednesday ahead of talks with Israeli officials.