UNITED NATIONS, Sept 21 (Andrew Quinn/Reuters) - The Quartet of Middle East peace mediators urged Israel on Tuesday to extend its settlement moratorium and called on Palestinian and Israeli officials to ensure their nascent direct peace talks continue.

The statement issued by the United States, the European Union, Russia and the United Nations on the sidelines of the UN General Assembly came just days before Israel's settlement is due to end on Sept. 30 -- a deadline that many fear imperils the fragile peace negotiations.

The Quartet noted that the commendable Israeli settlement moratorium instituted last November has had a positive impact and urged its continuation, said the statement, a draft of which was first seen by Reuters on Monday.

The Palestinians have threatened to leave the negotiations if settlement construction resumes when the partial moratorium expires, while Israel has said it will not extend the freeze, even for a limited period.

The United States is trying maintain momentum in the peace talks, which resumed on Sept. 2 in Washington with a diplomatic push from President Barack Obama, and has set a target of resolving the main issues in the decades-long dispute within a year.

State Department spokesman P.J. Crowley said US Middle East peace envoy George Mitchell held a number of meetings with both Israeli and Palestinian officials on Tuesday, including at least one meeting where all three sides met together.

Crowley said that meeting was attended by the chief negotiators for Israel and the Palestinians, Yitzhak Molcho and Saeb Erekat.

We are working as hard as we can demonstrating our commitment to the process and encouraging the parties to do everything possible to keep the negotiations moving forward, Crowley told a news briefing.

He said the three discussed the possibility of future meetings among Obama, Israeli Prime Minister Benjamin Netanyahu and Palestinian President Mahmoud Abbas, but added he was not aware there are any scheduled at this point.

POWER PROBLEMS

A planned news conference by Quartet representatives including Mitchell, UN Secretary General Ban Ki-moon, Russian Foreign Minister Sergei Lavrov, European Union foreign policy chief Catherine Ashton was scrapped at the last minute, a cancellation UN officials attributed to power problems in the building and schedule delays.

Crowley denied the delay reflected any division of opinion over the statement or the way forward on the peace progress, saying he was not aware of any controversy during the meeting.

I can attest to the technical challenge, Crowley said, saying an elevator outage was part of the problem. We all walked up six flights of stairs to the Quartet meeting, he said.

The final Quartet statement encouraged the parties to work together to find a way to ensure that negotiations continue in a constructive manner, a line that did not appear in the draft statement and appeared to put the onus on both Palestinians and Israelis to bridge the impasse.

Israeli President Shimon Peres met Palestinian President Mahmoud Abbas in New York on Monday, according to a diplomatic source, and said on Tuesday the peace negotiations were important to avoid a Middle East overrun by Iran, which is the main backer of the Islamist Palestinian Hamas group.

None of us would like to see the Iranians running the Middle East. ... One way to overcome this danger is really to go for peace. Israel is wholeheartedly today for peace, Peres told reporters.

The Jewish settlements on the West Bank, which Israel seized during a 1967 war, are deemed by the World Court to be illegal, a finding disputed by Israel. Palestinians fear the enclaves will deny them a viable and contiguous country.

Netanyahu, whose coalition government is dominated by pro-settler parties, has said he will not extend the construction moratorium but could limit the scope of further building in some settlements.

The status of Jerusalem, the fate of Palestinian refugees, the borders of a Palestinian state and security arrangements are the main issues Netanyahu and Palestinian President Mahmoud Abbas would have to resolve to secure a permanent peace deal. (Additional reporting by Arshad Mohammed and Missy Ryan; Editing by Cynthia Osterman and Peter Cooney)