Thousands of people packed Jerusalem's tense Old City on Friday for the burial of veteran Al Jazeera reporter Shireen Abu Akleh, after Israeli police stormed the start of the funeral procession.

Israel and the Palestinians have traded blame over the fatal shooting of the Palestinian-American on Wednesday during an Israeli raid in the occupied West Bank.

The interim findings of an Israeli army investigation could not determine who fired the bullet that killed Abu Akleh, the military said.

But an army statement noted a soldier could have fired the bullet that killed the 51-year-old journalist, in what Al Jazeera called a deliberate "killing in cold blood".

"The investigation shows two possibilities for the source of the shot that killed her," the army said.

The first could have been "massive fire of Palestinian gunmen (at Israeli soldiers), as part of which hundreds of bullets were shot from a number of locations."

"The other option is that during the gunfight, one of the soldiers shot a few bullets from a jeep using a telescopic scope at a terrorist who was firing at his vehicle."

TV images showed Abu Akleh's coffin nearly falling to the ground as Israeli police grabbed Palestinian flags from the crowd around the procession outside Saint Joseph's hospital in Israeli-annexed east Jerusalem.

Israel forbids public displays of Palestinian flags and often storms individuals who hoist them at rallies or protests in the city.

A senior Palestinian figure, Hanan Ashrawi, tweeted that "savage #Israeli 'special forces' viciously attack the funeral procession bearing the coffin" of Abu Akleh as it left St. Joseph's hospital.

"The inhumanity (of) Israel is on full display", said the former top Palestine Liberation Organization official.

Sister of all Palestinians

Thousands of mourners attended the funeral at a church in Jerusalem's Old City in the afternoon.

Roads were closed along the route of the procession as Israel bolstered security to "ensure the funeral takes place safely and without violence that could endanger participants or others", an Israeli police spokeswoman said.

In a sign of Abu Akleh's prominence, she was given what was described as a full state memorial on Thursday at Palestinian president Mahmud Abbas's compound in Ramallah before being transferred to Jerusalem.

"Her voice entered every home, and her loss is a wound in our hearts," said mourner Hadil Hamdan.

The United States, European Union and United Nations have backed calls for a full investigation into Abu Akleh's killing.

Israel has publicly called for a joint probe and stressed the need for Palestinian authorities to hand over the fatal bullet for forensic examination, but the Palestinian Authority has rejected holding a joint probe with the Jewish state.

Grief over her killing spilled beyond Palestinian territories, with protests erupting in Turkey, Sudan and elsewhere.

She "was the sister of all Palestinians," her brother Antoun Abu Akleh told AFP.

West Bank violence 

The European Union urged an "independent" probe while the United States demanded the killing be "transparently investigated", calls echoed by UN human rights chief Michelle Bachelet.

PA official Hussein Al-Sheikh, a close Abbas confidant, said the Palestinian "investigation would be completed independently".

An initial autopsy and forensic examination were conducted in Nablus in the West Bank hours after her death.

Fresh violence erupted on Friday in the West Bank, during an Israeli raid on the Jenin refugee camp. The Palestinian health ministry said 13 Palestinians were wounded in the clashes, one of them seriously.

An AFP photographer at the scene said Israeli forces had surrounded the home of a suspect, besieging two men inside and firing anti-tank grenades at the house in an effort to flush them out.

The Israeli army said its forces were acting to "apprehend terrorist suspects".

In a separate incident near Ramallah, soldiers "identified a suspect throwing a brick at an Israeli car and trying to open its doors near Beit El" settlement, the army said, adding that soldiers shot and wounded him.

Tensions had already risen with a wave of attacks that have killed at least 18 people in Israel since March 22, including an Arab-Israeli police officer and two Ukrainians.

A total of 31 Palestinians and three Israeli Arabs have died during the same period, according to an AFP tally, among them perpetrators of attacks and those killed by Israeli security forces in West Bank operations.