The fragile peace between rival Palestinian factions in Lebanon has been jeopardized by Monday's assasination of senior Fatah official Kamal Medhat, experts warned on Tuesday.

Medhat was killed, alongside three others, in a massive explosion that tore through his convoy, hurling his car from the road into a field near the Mieh Mieh camp outside Sidon. He had been visiting the camp to solve a dispute between rival families that had escalated into armed clashes, killing two people over the weekend.

Medhat was a key peace-broker between rival factions in Lebanon's 12 Palestinian camps and his death has raised concerns that the delicate balance of power in the Palestinian community could be destabilized.

Security experts and those familiar with Palestinian politics told The Daily Star that Medhat had been one of the most important promoters of Palestinian unity in the country.

They warned his death could undermine what one described as a "tacit agreement" between Fatah and Hamas not to engage in the violence that has characterized their relations elsewhere.

A source with extensive knowledge of Lebanese-Palestinian relations said that Medhat had played a unique role in bringing the Palestinian community in Lebanon together. "He was trying to do his best to unify the Palestinian cause," he said. "He believed that if they showed a disunited front to the Lebanese, it would be harder to get what they want. It's not going to be easy to find a man with all these qualities to replace him. I don't see it coming soon."

The source said there was "great anger" among Medhat's allies at the killing. "Let us hope that there are no repercussions, but it's a terrible crime" he said. "It's a very sensitive issue." Timur Goksel, a former UNIFIL staffer with more than two decades of experience in Lebanon, agreed that Medhat's killing was a "very significant" blow to Palestinian unity.

"He was the guy who kept the Palestinians together, so it's a negative development for them," he said. "They were keeping some semblance of unity. He was telling them to not to offend the Lebanese state. He really deserves most of the credit for keeping the Palestinians out of Lebanon's troubles in recent years."

"This is scary because it could cause a serious split, and they can't afford any more splits. I don't know if anyone will be able to step into replace him," he said. "I don't know whether they will be able to hold it together after this."

Retired Lebanese army General Elias Hanna said that the killing was certain to have an effect on relations between rival Palestinian factions. "What he was doing will stop for a while," he predicted. "Relations between Hamas and Fatah will be affected. They might appoint a replacement, but they won't be as efficient. This guy was experienced and that's irreplaceable."

He said security measures among Palestinian officials will be stepped up after the attack. "The PLO and PA will reconsider its security steps in Lebanon. They will have to reshuffle what they were doing here."

The killing has been roundly condemned by Palestinian leaders, who accused Israel of being behind the blast in a bid to sow discord in the camps.

Analysts agreed that Israel could have been behind the killing, but said that it was too early to apportion blame for Medhat's death. "Whoever did this had knowledge about Medhat and what he was doing, and they were able to plant the explosives," said Hanna. "We can't exclude Israel from the job, but there are a lot of unknowns."