United States Middle East envoy Anthony Zinni began his second attempt at mediation over the weekend much as he began the first, with fresh incidents renewing tensions between Israelis and Palestinians.

After three weeks of relative calm following Palestinian President Yasser Arafat appeal for an end to violence, Israel seized what it said was a shipment of Iranian arms bound for Palestinian terrorist organizations.

The estimated 50 tons of rockets, anti-tank missiles, small arms, explosives and mines were discovered Saturday, two days after the Israeli navy seized the Palestinian-owned and manned ship in the Red Sea, Israeli officials said.

"This is a very grave affair which unveils the true face of the Palestinian Authority, an authority which is completely infested with terror," Israeli Prime Minister Ariel Sharon told reporters on Sunday.

Palestinian Authority officials said they knew nothing about the ship and charged the Israelis with trying to undermine Zinni’s second attempt at negotiations in the troubled region.

Zinni hopeful

Zinni did not comment on the seizure after meeting with Palestinian parliament speaker Ahmed Korei in the West Bank on Saturday. He said only that he was optimistic on his first trip back to the region since a spate of suicide bombings and Israeli retaliatory strikes cut short his efforts last month.

"The focus is on security and building confidence, ensuring that we create a situation and environment that eliminates terror, that we begin a process that will lead us to beyond the ceasefire," and into the peace talks, he said after meeting with Israel's Foreign Minister Shimon Peres. "It is a long road and a long path."

Violence in which three Israelis and three Palestinians died cast a cloud over Zinni's initial trip to the Middle East last November. The incidents began a spiral of violence that lead to a spate of suicide bombings and shootings by Palestinian terrorist organizations and retailiatory military strikes by Israel.

Like last time, one of Zinni’s first goals will be to get both sides to agree to a cease-fire. Zinni will then most likely try and implement the Mitchell report, a series of recommendations by American senator George Mitchell to jump-start the peace process. Among the recommendations is the immediate cease-fire, followed by a cooling off period and a series of confidence-building measures on either side.

EU's Solana will join Zinni in mediation

The envoy, who has a reputation as a hard-nosed, straight-talking mediator, will hold tri-lateral talks with US, Israel and Palestinian representatives Sunday. He said he plans to fly back Monday and return again to the Middle East in 12 days.

The European Union's foreign policy chief also plans a trip to the region before continuning on to Egypt and Jordan. Spain's Javier Solana is due to arrive Sunday evening as part of the joint strategy the US and the EU have agreed to in mediating the Middle East conflict.

Tensions could erupt again before both mediators leave. Israel plans to prevent Arafat from attending Orthodox Christmas celebrations in Bethlehem on Sunday. It would be the second time in a month that the government has prevented the Palestinian leader from entering Bethlehem.

Israel said Arafat could lift the ban by arresting militants it claims are responsible for the murder of an Israeli cabinet minister.