WASHINGTON - US President Barack Obama has urged Israeli and Palestinian leaders not to let the chance of a permanent peace deal "slip away".

"This moment of opportunity may not soon come again," he said, pledging US support for the new negotiations.

Mr Obama spoke the day before a new round of direct talks between Israeli PM Benjamin Netanyahu and Palestinian leader Mahmoud Abbas was due to begin.

Earlier, he condemned the "senseless slaughter" of four Israeli settlers.

They were shot dead by gunmen near the West Bank city of Hebron on Tuesday, with the armed wing of Islamist movement Hamas, which controls the Gaza Strip and opposes peace talks with Israel, saying it had carried out the attack.

And in another attack, two Israelis were shot and wounded on Wednesday in the West Bank at Rimonim Junction, near the Jewish settlement of Kochav Hashahar.

Mr Obama spoke at the White House on Wednesday evening after meetings with Mr Netanyahu, Mr Abbas, Jordan's King Abdullah II and Egyptian President Hosni Mubarak.

President Obama has started what will be an intensive diplomatic push. He will have been pleased by what seemed to be a warm handshake between Mr Abbas and Mr Netanyahu.

Even so, Mr Abbas is insisting that Israel must stop building homes for Jews in the occupied Palestinian territories.

Mr Abbas has threatened to walk out of the talks on the settlement issue. It's not clear where the compromise will come from. Warm words alone won't do it - but perhaps Mr Netanyahu's were a start.

There might not be room for many more failures. The conflict is changing. A religious war is now being grafted on what used to be fundamentally a competition for territory between two national movements. You can make deals with nationalists. It's much harder with people who believe they're doing God's work.

His remarks came on the eve of the first direct negotiations between Israeli and Palestinian leaders in 20 months, which he said were "intended to resolve all final status issues".

Mr Obama said the goal of the talks, which are expected to last a year, was a permanent settlement that ended the Israeli occupation that began in 1967 and resulted in an independent, democratic Palestinian state existing peacefully beside Israel.

He said the US could not impose peace on the two parties, and that the US could not want peace more than them.

And he praised Mr Abbas and Mr Netanyahu as leaders "who I believe want peace".