A Palestinian official said on Sunday Israeli Prime Minister Benjamin Netanyahu delivered a blow to peace talks before they start next month as scheduled.

“The preconditions” which Netanyahu made on Sunday that the Palestinians should recognize Israel as the state of Jews “are a relapse to the negotiations before they start,” said Wassel Abu Yousef, a member of the Executive Committee of Palestine Liberation Organization (PLO).

“There is a Palestinian rejection to any Israeli demand to recognize Israel as a Jewish state. This is one of the Palestinian taboos,” Abu Yousef told Xinhua.

In his first comments about the direct talks that the United States invited Israel and the Palestinians to begin on Sept. 2 in Washington, Netanyahu predicted “difficult but possible” agreement with the Palestinians.

The PLO accepted the U.S. invitation on Friday after months of standstill, bypassing pledges not to go to face-to-face talks before Israel clearly announces a freeze on all settlement constructions in the occupied West Bank and East Jerusalem.