WASHINGTON, Aug 13 (Reuters) - US Secretary of State Hillary Clinton spoke with Israeli Prime Minister Benjamin Netanyahu about issues blocking direct peace talks with the Palestinians as the Obama administration boosted pressure for talks to begin as soon as possible, the State Department said on Friday.

Clinton telephoned Netanyahu on Thursday evening, and also discussed the issue with the foreign ministers of Jordan and Egypt, State Department spokesman P.J. Crowley said in message on Twitter.

Secretary Clinton continued the US push for peace in the Middle East last evening with calls to regional leaders, Crowley said, adding that her talks with Netanyahu focused on issues to be resolved for direct negotiations to begin.

Clinton's telephone calls followed a trip to the region by US Mideast negotiator George Mitchell this week in which he sought to break down the final barriers to direct peace negotiations, which US President Barack Obama hopes to see launched in coming weeks.

Palestinian President Mahmoud Abbas indicated on Monday he could go to direct talks, provided they were based on a March 19 statement by the Quartet of Mideast peace mediators -- the United States, the European Union, Russia and the United Nations.

But Israeli newspapers said Netanyahu told Mitchell on Wednesday he wanted talks to start immediately without any such precondition -- dampening hopes for an imminent breakthrough.

US officials have said they are working with other Quartet representatives on a possible statement, which EU High Representative Catherine Ashton said, in a letter seen by Reuters, would be issued early next week if both parties agree to move forward to direct talks.

The Quartet says Israel should halt settlement building in the West Bank and reach a full peace agreement with the Palestinians within 24 months, creating a state on the basis of borders that existed before the 1967 Middle East war.

Indirect peace negotiations mediated by Mitchell have made little discernible progress.

Obama wants the peace process to return to the level it broke off at nearly two years ago, when Israel went to war in the winter of 2008-09 to stop rockets being fired from the Gaza Strip by Hamas militants.

The stepped-up diplomacy comes as a partial 10-month moratorium on Israeli settlement building in the occupied West Bank, ordered by Netanyahu last November, is due to end on Sept. 26 -- raising a potential roadblock to further dialogue.

Abbas refuses to engage in direct talks unless Netanyahu agrees to a clear agenda. Without one, say the Palestinians, Netanyahu may propose terms for a peace treaty that are completely unacceptable, and leave Abbas looking like a rejectionist when he turns them down.