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

Islamic Jihad, the only Palestinian Arab faction boycotting the vote, claimed responsibility. Palestinian leader Mahmoud Abbas accused the group of trying to sabotage the January 25 election.

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

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

The explosion wrecked a fast-food restaurant specializing in grilled meat sandwiches, “The Mayor’s Shwarma.” It is located in a run-down area of downtown Tel Aviv that has been hit repeatedly by Palestinian Arab attackers.

Twenty people were wounded, one of them seriously, and the 22-year-old bomber was killed.

“I ran and saw the terrorist in two pieces,” Shlomo Eliav, 49, who owns a kiosk around the corner and has experienced several attacks, said. “I’m sick of this. I’m thinking of moving” to another part of town, he said.

Blood, shattered glass, and debris covered the ground near shops, as helmeted security forces cordoned off the area. A crowd gathered outside the restaurant, surrounding a weeping elderly man in a fur hat who shouted out the name, “Pini, Pini.”

This was the seventh suicide bombing aimed at Israelis since Palestinian Arab terrorists declared an unofficial truce in February 2005. Islamic Jihad claimed responsibility for all – six in Israel and one at a West Bank army checkpoint.

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

The terrorist group released a video made by the bomber before the attack. He said he was “offering himself to avenge the blood of martyrs.”

Brandishing a rifle and posing before a black Islamic Jihad flag, he said he carried out the bombing in response to Israeli attacks on civilians and militants.

At the family home, a four-story building in Nablus, Antar’s mother was crying hysterically and could not talk. His brother, Sameh, 32, appeared puzzled.

“I can’t say anything about those who sent him,” Sameh told the AP. “All I can say is that my brother had everything. It seemed he wanted martyrdom, and he got what he wanted.”

Israeli officials tried to link the bombing to Iran, which backs Islamic Jihad. Public Security Minister Gideon Ezra said Iranian TV was the first to broadcast the Islamic Jihad claim of responsibility.

“There is a trail to Iran and to Syria, where the extremist organizations are,” Mr. Ezra told Israel TV.

Israeli defense officials huddled late yesterday to discuss a response, but Mr. Olmert’s options appeared limited. Harsh retaliation might backfire among moderate Israeli voters, Mr. Olmert’s key constituency.

On Tuesday Mr. Olmert said he was interested in talks toward a peace treaty with the Palestinian Arabs on condition they dismantle violent groups as stipulated in the internationally backed “road map” peace plan.

Mr. Sharon is believed to have favored a long-term interim arrangement to test Palestinian Arab intentions, and has been skeptical of Mr. Abbas’s ability to rein in terrorists.

Mr. Olmert is running for prime minister in March 28 elections as Mr. Sharon’s successor. Mr. Sharon, felled by a massive stroke January 4, remains in a coma.

Several times in past years, Palestinian bombing attacks have helped decide Israeli elections, pushing voters to hard-line parties that pledge to punish the Palestinian Arabs at the expense of parties promoting the peace process.

Mr. Sharon founded his centrist party, Kadima, in November, bolting Likud because of its opposition to his peace moves. Likud reinforced its hawkish stand by choosing a hard-line former premier, Benjamin Netanyahu, as its leader.

Polls show Mr. Olmert and Kadima far ahead, with Likud losing most of its strength.

A Sharon aide, Raanan Gissin, said Israelis have moved solidly to the moderate center now, advocating withdrawal from much of the West Bank. “One terrorist attack or two terrorist attacks are not going to sway them,” Mr. Gissin said.

He blamed inaction by Mr. Abbas’s security forces for the Tel Aviv attack, charging that terrorist groups have “moved into the void.”

Mr. Abbas harshly condemned the bombing, which countered his efforts to control the terrorists by bringing them into the power structure. The larger of the two Islamic groups, Hamas, is running candidates for parliament and has mostly stopped attacks against Israel over the past year, but Islamic Jihad persists.

“This is sabotage and aimed at sabotaging the elections, not only the elections, but also the security of Palestinians,” Mr. Abbas told reporters at his office in the West Bank city of Ramallah. “The culprits must be punished.”