(JTA) — A senior Palestinian official said U.S. Secretary of State John Kerry “guaranteed in writing” that Israeli-Palestinian peace talks would start with the 1967 lines.

American officials, however, denied the existence of such a document, The New York Times reported Tuesday.

Nabil Shaath, the Palestinian commissioner for international relations, told the newspaper that the Palestinians agreed to restart the peace talks as a direct result of the guarantee.

State Department spokesman Marie Harf told the Times in an emailed statement, “We have always said that if you don’t hear news about the talks from senior U.S. officials, you can’t count on it being reliable. This is a good example.”

An Israeli spokesman would not comment to the Times on the guarantee.

The Palestinians have insisted that talks be based on the 1967 lines, and the United States has agreed though with agreed-upon land swaps. Israel has insisted there be no preconditions for talks.

Israel last week complained to the United States about Palestinian officials leaking information about the relaunched peace talks, despite both sides agreeing to honor a request by Kerry that information about the negotiations be kept under wraps.