(Reuters) - In a move that heightened tensions with Israel and could lead to cuts in U.S. aid, the Palestinians on Friday delivered to U.N. headquarters documents on joining the Rome Statute of the International Criminal Court and other international treaties.

The chief Palestinian observer at the United Nations, Riyad Mansour, and U.N. spokesman Farhan Haq confirmed handover of the diplomatic documents at the world body's headquarters.

"This is a very significant step," Mansour said. "It is an option that we are seeking in order to seek justice for all the victims that have been killed by Israel, the occupying power."

The U.N. press office issued a statement saying the Palestinians had delivered documentation to join 16 international treaties. "The documents are being reviewed with a view to determining the appropriate next steps," it said.

While President Barack Obama supports an eventual independent Palestinian state neighboring Israel, U.S. officials have argued against unilateral moves like Friday's, warning they could set back the peace process.

"We are deeply troubled by Palestinian action regarding the ICC," a senior State Department official said. "It should come as no surprise that there will be implications for this step, but we continue to review," the official said, referring to U.S. aid to the Palestinian Authority.

Washington sends about $400 million in economic support aid to the Palestinians every year. Under U.S. law, that aid would be cut off if the Palestinians used membership in the International Criminal Court to make claims against Israel.

The Hague-based court looks at cases of severe war crimes and crimes against humanity, such as genocide.

According to the Rome Statute, the Palestinians will become a party to the court on the first day of the month that follows a 60-day waiting period after depositing signed and ratified documents of accession with the United Nations in New York.

The ICC move paves the way for the court to take jurisdiction over alleged crimes committed in Palestinian lands and investigate the conduct of both Israeli and Palestinian leaders over more than a decade of bloody conflict. Neither Israel nor the United States belongs to the ICC.

Mansour said the Palestinians have also formally requested retroactive ICC jurisdiction "with regard to the crimes committed during the last war in Gaza." He was referring to Israel's 50-day war against Hamas militants in the Gaza Strip this past summer.

More than 2,100 Palestinians, 67 Israeli soldiers and six civilians in Israel were killed in the July-August war.

Regarding the threat of possible U.S. sanctions for joining the ICC, Mansour said: "It is really puzzling when you seek justice through a legal approach to be punished for doing so."

Israeli Prime Minister Benjamin Netanyahu on Thursday said President Mahmoud Abbas' action would expose the Palestinians to prosecution over support for what he called the terrorist Hamas Islamist group. He vowed to take steps to rebuff any potential moves against Israel.

"We will take steps in response and defend Israel's soldiers," Netanyahu said in a statement.

Silvan Shalom, Israeli minister for infrastructure and regional cooperation, told Israel's Channel Two TV that the Palestinians' action violated the Oslo agreements, which could lessen Israel's willingness to make any future deals.

Netanyahu himself was an opponent of the Oslo peace process, however, and called the accords deeply flawed.

The other signed treaties the Palestinians delivered to the United Nations include the U.N. Convention Against Transnational Organized Crime, the U.N. Convention on the Law of the Sea, two additional protocols to the Geneva Conventions and the Convention on Cluster Munitions.

The Palestinian government signed the Rome Statute on Wednesday, a day after a bid for independence by 2017 failed at the U.N. Security Council.

Palestinians seek a state in Gaza, the West Bank and East Jerusalem - lands Israel captured in the 1967 Middle East War.

Momentum to recognize a Palestinian state has built since Abbas succeeded in a bid for de facto recognition of Palestinian statehood at the U.N. General Assembly in 2012, which made Palestinians eligible to join the ICC.

(Additional reporting by Lesley Wroughton and Patricia Zengerle in Washington and Dan Williams in Jerusalem; Editing by Bill Trott, Dan Grebler and Bernard Orr)