West Bank ? President Barack Obama warned Mahmoud Abbas in a letter that U.S.-Palestinian relations might suffer if the Palestinian leader refuses to resume direct peace talks with Israel, a senior PLO official said Saturday.

The White House had no comment Saturday. However, the Obama administration has been pushing Abbas hard in recent days to move quickly to face-to-face negotiations.

The PLO official said Obama sent the letter — the strongest U.S. warning to Abbas yet — on July 16.

Abbas insists he will only negotiate once Israel commits to the idea of a Palestinian state in the West Bank, Gaza and east Jerusalem, with minor modifications. He also wants Israel to freeze all settlement construction in those areas.

Israeli Prime Minister Benjamin Netanyahu refuses to be pinned down ahead of talks and has put in place only a 10-month freeze in housing starts in the West Bank that is due to expire in September.