RAMALLAH — Palestinian Authority President Mahmoud Abbas again charged Thursday that Israel was responsible for the death of Al Jazeera journalist Shireen Abu Akleh, fatally shot the previous day under disputed circumstances, and vowed that the matter would be taken to the International Criminal Court because Israel “cannot go unpunished.”

Abu Akleh, 51, was shot in the head during clashes between Israeli troops and Palestinian gunmen while covering an Israeli army operation in the West Bank city of Jenin on Wednesday. The Palestinians blamed Israel for her death, while Israeli officials said Palestinian gunmen may have fired the fatal shot.

At a state memorial for Abu Akleh held at the presidential palace in Ramallah attended by thousands, Abbas reiterated that the PA would not participate in a joint investigation, also repeating the unproven claim that Israel was responsible for the death of the journalist.

“They committed the crime and we do not trust them,” Abbas said, adding that the PA will instead “turn immediately to the International Criminal Court to prosecute the criminals.”

“We hold the Israeli occupation authorities totally responsible for her killing,” Abbas said. “This crime cannot go unpunished.”

Thousands of Palestinians, including Abu Akleh’s Al Jazeera colleagues, accompanied her body through the streets of Ramallah to the PA presidential compound. The crowds made an unusual sight at Abbas’s office, which has rarely opened to the general public in recent years.

As the memorial ceremony wrapped up in Ramallah, several dozen protesters chanted slogans against the PA’s policy of security coordination with Israel. When Israeli forces enter Palestinian areas, they often inform their Palestinian Authority counterparts to avoid confrontations.

“Why is there coordination [with Israel] when we’re under fire by their army’s bullets,” demonstrators chanted.

Abu Akleh’s body was later borne in an ambulance to Jerusalem via the Qalandiya checkpoint, followed by a large procession of Palestinians. In footage broadcast by Al Jazeera, some masked Palestinians could be seen raising assault weapons and firing in the air.

On Friday, Abu Akleh is set to be buried in her native Jerusalem. The funeral is expected to attended by thousands of mourners, including diplomats and Palestinian politicians.

The ICC is investigating alleged abuses by Israeli forces and Palestinian terror groups in the West Bank and the Gaza Strip. Jerusalem says the ICC has no jurisdiction in those areas, since the Palestinians do not have a state. Israel is not a member of the ICC, and has accused it of bias, but its citizens could be subject to arrest abroad if warrants are issued.

The European Union has urged an “independent” probe into the reporter’s death, and the United States demanded the killing of Abu Akleh, who held American citizenship, be “transparently investigated,” calls echoed by UN human rights chief Michelle Bachelet.

“We’ve offered our help. No one’s taken us up on this yet, but we stand ready to assist if asked,” George Noll, the Palestinian Affairs Unit chief at the US embassy, told The Times of Israel.

Abu Akleh’s family and friends have demanded a more strident American response to her killing, for which many of them blame Israel.

“I understand the frustration. This is a frustrating place to be if you’re working for peace…The frustration is understood. There’s limits to what we can do, we don’t have jurisdiction overseas,” Noll said.

Israel has called on the Palestinians to conduct a joint investigation into the death, but that request was formally rejected by the PA on Thursday.

In response, Israeli officials criticized the PA’s refusal to work together, with unnamed sources telling Army Radio that “those who have nothing to hide do not refuse to cooperate.”

Communications Minister Yoaz Hendel said that “anyone who claims the IDF killed the journalist is not doing so on the basis of an investigation or facts, but propaganda.”

An initial autopsy of Abu Akleh’s body by Palestinian coroners found that it was “not possible” to tell whether she was killed by Israeli or Palestinian gunfire.

Meanwhile, an initial internal IDF probe reportedly found that though she was likely standing near armed terrorists, Israeli troops did not fire at her.

Channel 12 reported that the bullet in question is a 5.56×45mm NATO round, which is used by both Israeli troops and Palestinian terrorists for weapons, including M16 and M4 assault rifles.

Abu Akleh was set to be buried in Jerusalem on Friday.

Her death came amid soaring tensions in the West Bank in recent weeks. Palestinian terrorists, many from the Jenin area, have crossed the fence into Israel to commit terror attacks, part of a bloody wave of violence that has left 19 people dead in Israel and the West Bank since late March.

Israeli forces have responded by stepping up raids and arrests in an attempt to restore order, and increasing its patrols along the West Bank border. The security operations have often led to armed clashes with Palestinians.

Agencies contributed to this report.