Tel Aviv, Israel ? A Palestinian suicide bomber posing as a peddler blew himself up in a Tel Aviv fast-food restaurant Thursday and wounded 20 people in an apparent attempt to destabilize the region a week before Palestinian elections.

Islamic Jihad, the only Palestinian faction boycotting the vote, claimed responsibility. Palestinian leader Mahmoud Abbas accused the group of trying to sabotage Wednesday’s election.

In a high-level security meeting to assess a response, Israeli Defense Minister Shaul Mofaz said Syria planned the attack and Iran funded it, but Israel would not hit back at the Palestinians, according to security officials speaking on condition of anonymity because they were not authorized to provide details to the media.

Mofaz cited “clear evidence” about Syrian and Iranian involvement, the officials said.

The Israeli response will be a key test for acting Prime Minister Ehud Olmert, who took over after Ariel Sharon suffered a massive stroke earlier this month. The bombing came two days after Olmert said he was ready to resume peace talks following Israel’s March election, provided Abbas disarms militants.

The bomber, who witnesses said posed as a peddler, walked into the restaurant and blew himself up even though most of the customers were sitting relatively far away at sidewalk tables, police spokesman Mickey Rosenfeld said.

Twenty people were wounded, one of them seriously, and the bomber was killed.

This was the seventh suicide bombing aimed at Israelis since Palestinian militants declared an unofficial truce in February 2005. Islamic Jihad claimed responsibility for all.

Islamic Jihad identified the assailant as 22-year-old Sami Abdel Hafez Antar from the West Bank city of Nablus.