Prime Minister Ehud Olmert sacked Israel's top negotiator on Gaza truce talks for publicly criticizing his demand that Palestinian militants hand over a captured Israeli soldier before any deal is clinched, officials said Monday.

The move threatens to roil the talks just weeks before Olmert is succeeded by the hawkish Benjamin Netanyahu, who wants Gaza's Hamas rulers toppled and likely would take a tougher line in the Egyptian-brokered negotiations.

Reaching a truce has implications beyond cementing the informal Jan. 18 cease-fire that ended Israel's war on Hamas. Without it, there is little chance of advancing already troubled talks to reconcile feuding Palestinian factions.

In related news, Al Qaeda's No. 2 warned Palestinians in Gaza against accepting a truce with Israel in an audio message posted on extremist Web sites, an Internet monitoring service said Monday.

Olmert abruptly announced last week that Israel would not reopen Gaza's long-blockaded borders — the main Israeli concession in any truce — until Hamas-affiliated militants freed Sgt. Gilad Schalit, seized in a June 2006 cross-border raid.

Amos Gilad, the sacked negotiator, opposed linking the truce deal with Schalit, and criticized Olmert's strategy in an interview last week with Israel's Maariv daily. After Gilad refused to apologize, Olmert gave him the boot, aides said.

"Due to the inappropriate public criticism leveled by Mr. Gilad, he cannot continue as the prime minister's envoy to any political negotiations," Olmert's office said in a statement. Aides said talks would not be affected by Gilad's dismissal.

A longtime adviser to the prime minister, Shalom Turgeman, will replace Gilad on the truce talks, Olmert aides said. Veteran negotiator Ofer Dekel will handle efforts to free Schalit. The officials spoke on condition of anonymity because of the secretive nature of the talks.

There was no immediate reaction from Gilad or Egypt.

Hamas shrugged off the development, with spokesman Fawzi Barhoum saying Israel "never intended to reach any agreement or closure on a truce or a prisoner exchange."

Hamas desperately wants Israel and Egypt to reopen their borders with Gaza, sealed after Hamas seized control of the territory nearly two years ago. But it rejects any linkage between a prisoner release and the truce negotiations.

Osama Bin Laden's deputy, the Egyptian-born Ayman Al-Zawahri, described truce negotiations as "plots and conspiracies" to defeat the Palestinians after Israel's "aricraft and artillery" failed, according to a transcript of his Internet message provided by the U.S.-based SITE Intelligence Group, a group that monitors extremist Islamic Web sites.

Bin Laden also issued an audio message on Gaza in January, urging Muslims to launch a holy war against Israel. Al-Qaida holds little influence among Palestinians, but its Gaza-related postings are likely meant to harness Muslim anger about the Israeli offensive.

Israel launched its Gaza offensive following years of Palestinian rocket attacks on its south. The sides declared separate cease-fires Jan. 18, but sporadic violence has persisted. Two rockets struck Israel on Monday and an Israeli aircraft fired missiles on a vehicle belonging to militants preparing an assault, the military said. No injuries were reported in any of the incidents.

A truce deal is key not only to the fate of Gaza's borders but also to any future power-sharing agreement between Hamas and the Fatah movement of moderate Palestinian President Mahmoud Abbas, who controls only the West Bank after his forces were routed in Gaza.

Efforts to form a unity government have failed in the past, but Israel's Gaza offensive gave both sides greater incentive to try to join forces.

Gaza can't end its international isolation unless it allows Abbas a foothold there. Abbas has overstayed his term as president, which ended in January, and needs a partnership with Hamas to shore up his dwindling political legitimacy.

For all that, a news conference at the Hamas-run Interior Ministry in Gaza on Monday did not bode well for reconciliation talks scheduled to begin in Egypt later this week.

Hamas officials played videotapes of what they said were Fatah loyalists confessing to relaying information about weapons warehouses, smuggling tunnels and the homes of Gaza political leaders to Abbas' West Bank government.

One of the loyalists said he thought the information was later transmitted to the Israeli military and used to locate targets hit during the war. But he provided no evidence to back that claim.