18 Injured as Israeli Riot Police Break Up Palestinian Protests : Mideast: Demonstrators seek release of Arabs jailed by Israel. Issue may hurt talks on West Bank, elections.

Thousands of protesters demanding the release of Palestinians in Israeli jails clashed violently with riot police Saturday on the occupied West Bank, heightening pressure on the government to free political prisoners before concluding the second phase of peace talks next week.

At least 15 protesters and three police officers were injured, and several dozen people were arrested, in separate incidents, the worst of which occurred outside Orient House, headquarters of the Palestine Liberation Organization in East Jerusalem.

Several hundred demonstrators there threw stones and bottles at police, who fired live ammunition, rubber bullets and tear gas. Riot officers clubbed several protesters, Palestinian security guards and journalists.

Similar protests were broken up by police, with live ammunition and rubber bullets, in the West Bank cities of Hebron, Tulkarm and Janin. In Nablus, troops dispersed a crowd of several hundred women, wounding two. The women had been carrying signs demanding that Israel release their loved ones. Two more protesters were injured by rubber bullets fired during a demonstration in Ramallah.

The clashes, among the most serious in months, followed a hunger strike launched last Sunday by about 2,000 prisoners, who have been taking only water and salt. In all, about 5,500 Palestinians are held in Israeli jails, many on charges of demonstrating against Israel.

Political analysts said the dispute over the prisoners could undermine progress toward an agreement on the second phase of the interim peace accord, which would extend Palestinian self-rule throughout the West Bank and set the stage for Palestinian elections. The target date for that agreement is Saturday, though Israeli officials have said it is unlikely the deadline will be met.

Under the 1994 pact that set up self-rule in the Gaza Strip and the West Bank town of Jericho, Israel agreed to release political prisoners. But PLO officials say at least 1,700 prisoners who should qualify under that agreement are still in prison.

Yasser Arafat, the PLO chief, last week made the phased release of prisoners a precondition for agreement with Israel on the second stage of the interim peace accord.

Israel contends that it has met its obligations, saying the remaining Palestinian prisoners fall outside the scope of the agreement and would pose a security risk if released. In any case, Israeli officials have said they would not release Palestinians who have been jailed for killing Israelis.

But the protests have increased pressure on Israeli officials, and Prime Minister Yitzhak Rabin on Saturday instructed members of the ministerial committee dealing with the prisoner issue to meet in the next few days.

Although most of Saturday’s battles between Palestinians and police occurred on the West Bank, protesters in Gaza City also clashed with a joint Israeli-Palestinian patrol, leaving one demonstrator injured. The protesters were on their way to a rally in support of the prisoners that attracted 2,000 Palestinians.

Protesters in East Jerusalem took refuge from riot police in the gated compound around Orient House, but they then threw bottles and rocks at border police, who responded by opening fire.

Palestinian official Faisal Husseini said the police action “was a provocative act which violates the whole basis of the peace process.” Speaking in Gaza, after a regular meeting of the Palestinian Authority, Husseini said the procession at Orient House had begun peacefully.

Orient House, as the home base of Palestinian political activity in East Jerusalem, is considered a symbol of the PLO’s claim to the predominantly Arab parts of the city, which were captured from Jordan in the 1967 Middle East War.

Israel says it will never relinquish control over any of Jerusalem. Talks on the future of the city are not due until 1996.