BEERSHEBA, Israel – Suicide bombers blew up two buses almost simultaneously in southern Israel on Tuesday, killing at least 15 people and wounding more than 80 others in the first Palestinian attack inside Israeli in nearly six months.

The twin blasts, claimed by the militant group Hamas, were likely to provoke a harsh Israeli response. Prime Minister Ariel Sharon met with top security officials and planned further talks later in the day.

“Israel will continue fighting terror with all its might,” Sharon said, pledging to push forward with Israel’s planned withdrawal from the Gaza Strip. The explosions came just hours after he presented his Likud party with the most detailed timetable yet for the pullout.

The buses burst into flames about 100 yards apart near a bustling intersection in Beersheba, the largest city in southern Israel, just 10 miles from the West Bank. Hamas issued a leaflet in Hebron — the closest Palestinian city to Beersheba — saying the attack was avenging Israel’s assassinations of two of its leaders earlier this year.

“People were screaming and yelling. Everybody was running,” said witness Tzvika Schreter, a 50-year-old college lecturer.

Rescue workers scoured the scene, cleaning up body parts and scattered pieces of the wreckage as dozens of onlookers gathered nearby. A hand with a ring lay on the ground, and blood was splattered on the walls of the mangled buses.

Police said the messy scene was complicating the recovery of bodies and warned the death toll could rise. They said the 15 people did not include the bombers. Israel’s Magen David Adom rescue service said 30 of the wounded were in serious or moderate condition.

Authorities stepped up security throughout Beersheba after the attacks, placing checkpoints on major roads and snarling traffic coming in and out of the city.

In the Gaza Strip, Muslim leaders praised the “heroic operation” over mosque loudspeakers.

Palestinian militants haven’t carried out a major attack inside Israel since March 14, when 11 people were killed in the port of Ashdod. After that attack, Israel assassinated Sheik Ahmed Yassin, the spiritual leader of Hamas, and his successor, Abdel Aziz Rantisi. Hamas has repeatedly pledged to avenge their deaths, but had taken little action before Tuesday.

“If you thought that the martyrdom of our leaders would weaken our missions and discourage us from Jihad, then you are dreaming,” the Hamas leaflet said.

Hamas and other Palestinian militant groups have carried out more than 100 suicide bombings over the past four years, but the pace of attacks has slowed considerably this year.

Israel has attributed the slowdown to its success in fighting militants and its contentious West Bank separation barrier — not a lack of effort by armed Palestinian groups.

Israel has arrested or killed dozens of militants in recent months, maintains dozens of roadblocks in the West Bank and places security guards near busy bus stops in Israeli cities.

But Israeli officials Tuesday repeatedly cited the barrier, which has drawn international condemnation, as the No. 1 reason for the slowdown. The structure of concrete and barbed wire, which is about one-quarter complete, has not yet reached the Hebron area.

“Unfortunately Israel has to lose more innocent civilians to prove to the world the necessity and justice of the fence,” said Dore Gold, an adviser to Sharon.

Earlier Tuesday, the Israeli army caught a Palestinian man with an explosives belt strapped under his clothing as he tried to cross into Israel from the Gaza Strip. Gaza is closed off from Israel, and militants have had trouble reaching Israel from there.

Palestinian leaders condemned the attack and called for an immediate cease-fire and resumption of peace talks. The European Union also condemned the bombing and called for an end to bloodshed in the Middle East.

“The Palestinian interest requires a stop to harming all civilians so as not give Israel pretext to continue its aggression against our people,” Palestinian leader Yasser Arafat said in a statement.

Sharon refuses to negotiate with the Palestinians. Instead, he has called for a unilateral withdrawal next year from the Gaza Strip and four isolated West Bank settlements. He says the moves will improve Israel’s security.

In Jerusalem, a Sharon ally in the Cabinet said the Gaza withdrawal could begin by the end of the year, or several months ahead of schedule.

The initial plan called for the withdrawals to be completed in four stages by September 2005. Each phase was to be presented to the Cabinet for approval.

With opposition mounting in Likud and in the Cabinet, Sharon is pushing for a swifter withdrawal. He also hopes to weaken settler resistance by making early advance payments on compensation that would encourage many of the 8,000 Gaza settlers to leave voluntarily, according to Sharon officials, who spoke on condition of anonymity.

The prime minister opened Tuesday’s meeting with Likud legislators with a warning not to sabotage the withdrawal. “You know my views on the subject. The disengagement plan will be implemented, period,” he said.

The first key date in Sharon’s timetable is Sept. 14, when the Cabinet is to approve the principles of compensating and evacuating settlers. Officials said advance payments would be authorized at that session.

On Sept. 26, Cabinet ministers will be given draft legislation for carrying out the withdrawal, and the bill will be approved by the Cabinet on Oct. 24, Sharon said. By Nov. 3, the legislation will be presented to parliament for a first of three votes.

Sharon has already lost two Likud battles over his pullout plan — a nonbinding referendum by party members and a convention vote. At least half of the 40 Likud members of parliament oppose the pullout.

Copyright © 2004, The Associated Press