JERUSALEM — Palestinian police have arrested some 30 Hamas activists in the southern Gaza Strip, said Palestine Liberation Organization leader Yasser Arafat.

Arafat, head of the Palestinian Authority that controls most of Gaza, announced the arrests after a meeting Tuesday with Israeli Tourism Minister Uzi Baram.

Palestinian officials said one of those arrested in the overnight sweep was just hours away from leaving for a suicide bombing mission in Tel Aviv.

"He had explosives and had shaved his beard," PLO official Sufayn Abu Zaide told Israel Television, adding that the Hamas member had "arranged to travel to the central bus station in Tel Aviv."

"He planned to blow himself up there at 3 a.m." on Tuesday, Zaide added.

The arrests, which resulted in part from intelligence information provided by Israel, came as Palestinian security officials were searching for Yehiya Ayash, according to Israeli sources.

Ayash, known as "the Engineer" for his expertise with explosives, is believed to be the Hamas mastermind behind several suicide bombings in Israel.

Israel Radio quoted a Palestinian police source as saying the search for Ayash continues.

The announcement of the arrests by the Palestinian police came days after Israeli security officials disclosed that they had infiltrated Hamas cells in the West Bank and had arrested at least 30 Hamas operatives there and in eastern Jerusalem.

The arrests were described by Israeli officials as dealing a severe blow to Hamas' terror operations against Israeli soldiers and civilians.

Meanwhile, Israel on Wednesday lifted the closure it imposed last week on the Palestinian self-rule enclave of Jericho in the West Bank. The move came after hundreds of Jericho residents rioted Monday at an army roadblock at one of the entrances to the city. Demonstrators burned an Israeli flag and hurled stones at Israeli border police, injuring three of them.

Israel sealed off Jericho from the rest of the West Bank on Aug. 23 after Palestinian officials arrested two Hamas members who had fled there, but refused to turn the pair over to Israeli authorities. Israel said the detainees are believed to have helped plan the Aug. 21 suicide bombing of a bus in Jerusalem.

They were identified as Abed Majid Dudin and Rajid Khatib, both from the West Bank town of Hebron. At a trial in a Palestinian military court in Gaza on Saturday, Dudin was sentenced to 12 years in jail and Khatib received a seven-year sentence.

Some Israeli officials questioned the speed with which the two were sentenced, saying the jail terms were handed down quickly in an effort to keep the two men out of Israeli hands.

Under the self-rule accord, the Palestinian Authority does not have to turn over to Israel any suspects held in Palestinian prisons until the conclusion of their jail sentences.

The Palestinian indictments against the pair did not directly link them to the bus attack. Instead, they were charged with endangering the interests and security of the Palestinian people, the Palestinian Authority and the Israelis.

Meanwhile, U.S. Middle East peace envoy Dennis Ross held separate talks Tuesday with Peres and Arafat in an effort to achieve progress in the ongoing Israeli-Palestinian negotiations for extending self-rule in the West Bank.

Both Ross and Peres predicted that the completed accord would be signed in Washington, D.C., in mid-September.

Among the 30 Hamas members arrested by Israel last week were Nasser Issa and Hatam Ismail, both from the Gaza Strip, who were suspected of having recruited the suicide bombers who carried out the Aug. 21 bus bombing in Jerusalem and the July 24 suicide bus bombing in Ramat Gan.

The head of the Shin Bet said that after breaking up a Hamas cell the security services had infiltrated, interrogations led to more arrests in recent days of Hamas operatives in the West Bank and eastern Jerusalem.

Among those detained was Haiman Sider, who is believed to have opened fire in a Jerusalem pedestrian mall Oct. 9, killing two people and injuring 13 others.

In the wake of those arrests, Israel lifted its closure of the West Bank on Sunday, which had been imposed after the Aug. 21 bus bombing.

Also on Sunday, Israeli and Palestinian officials attended a signing ceremony in Cairo to hand over eight additional spheres of civilian authority in the West Bank to the Palestinians.

Israeli Gen. Oren Shahor and Palestinian negotiator Jamil Tarifi signed the 22-page agreement, which gives the Palestinians administrative control over the areas of agriculture, postal services, insurance, gasoline, industry and commerce, labor, municipal affairs and statistics.

Israel officially recognized Palestinian rights to water sources in the West Bank. In turn, the Palestinians agreed to defer the issue of who would have ultimate control over water resources until the permanent-status negotiations slated to start next year. The two sides were expected to discuss water allocation issues for the interim period during their talks in Eilat this week.

Ross also said the Clinton administration is planning two major conferences to help raise $100 million in aid for the Palestinian Authority, according to Israeli Radio.

Meanwhile, the fourth victim of last week's Jerusalem bus bombing was laid to rest after her body was identified last Friday. Family members of Hannah Na'eh, 45, of Jerusalem identified her after pictures of the body were published in the media last week. A divorced mother of three from a deeply religious family, she lost contact with them after ceasing to be observant.

A memorial service was held Sunday night for the victims of last week's bomb attack. The service, held at the site of the bombing in Jerusalem's Ramat Eshkol neighborhood, was organized by the Likud opposition party.