The Islamic group Hamas will continue to fight Israel "by all means" and will not support a cease-fire called by Palestinian leader Yasser Arafat, the militant group's spiritual leader said Tuesday.

International pressure to keep the truce on track was growing, with CIA Director George Tenet expected to head to the region on Wednesday to promote Israeli-Palestinian security cooperation.

Despite the diplomatic push, Israeli Prime Minister Ariel Sharon had harsh words for Arafat. He's "a murderer. He's a pathological liar," Sharon said in an interview with Russian TV channel NTV, which was broadcast on Israel's Channel Two.

In his strongest attack on Arafat since taking office in March, Sharon complained that Arafat is welcomed around the world "with a red carpet," when instead of acting like a head of state, "he behaves as the head of terrorists and murderers."

Sheikh Ahmed Yassin said the group, which claimed responsibility for the terror bomb that killed 20 people in Tel Aviv on Friday night, wants "to tell the world that our Palestinian people are not going to kneel down, will not surrender and will continue in this intefadeh."

"When we are talking about the so-called cease-fire, this means between two armies," Yassin told The Associated Press. "We are not an army. We are people who defend themselves and work against the aggression."

In the Gaza Strip, Yassin was among 2,000 Palestinians marking the 34th anniversary of the 1967 Mideast war with a march. Demonstrators chanted, "The intefadeh will continue until victory!" and carried posters of Arafat and Yassin.

A Hamas spokesman in Gaza, Mahmoud Zahar, said Hamas will "continue the intefadeh by all means and everywhere in occupied Palestine of 1948 or in occupied lands in 1967."

Early Tuesday, a leaflet signed in the name of the militant wings of Hamas and Arafat's Fatah group said a cease-fire would be respected. However, within hours key Hamas figures were disputing the idea and suggesting the leaflet might not be authentic.

Hamas support for the cease-fire Arafat called Saturday is seen as vital to its success.

The Islamic group, which has claimed many bomb attacks against Israel, said the bomber who blew himself up outside a Tel Aviv disco on Friday night was a Hamas member.

U.S. Secretary of State Colin Powell urged Arafat in a telephone call late Monday to arrest those responsible for the Tel Aviv nightclub bombing, a U.S. official said on condition of anonymity.

Violence Continues

Israeli Foreign Minister Shimon Peres said a reduction of Palestinian violence in recent days shows a convincing cease-fire had begun.

But despite the relative break in the eight months of escalated fighting, several Palestinians were injured Tuesday in clashes in Hebron and Ramallah in the West Bank, Palestinian witnesses said.

Also in the West Bank, Ashraf Mahmoud Bardawil, 27, a Fatah activist in the Tulkarem area, was critically injured in an explosion in his car, according to a local hospital director and Bardawil's family. The cause wasn't clear.

North of Ramallah, Israeli soldiers opened fire Tuesday with rubber-coated steel bullets on Palestinians throwing stones after the army refused to let them by a checkpoint, Palestinian witnesses said. Ten Palestinians were injured. The army said it fired on 600 demonstrators to disperse them.

In Hebron, Palestinian doctors said at least 2 people among about 30 people throwing stones and Molotov cocktails were injured by rubber bullets. An Israeli army spokesman said only that a Palestinian in Hebron threw an iron bar at soldiers who responded with tear gas and rubber bullets. It wasn't clear if the incidents were the same.

Near the city, an exchange of fire erupted between security forces of the two sides and one Palestinian officer was injured in the leg. The Israeli army said soldiers shot after they were fired on.

In the West Bank, Palestinian gunmen fired at Israeli cars at two points early Tuesday but no injuries were reported.

The Associated Press contributed to this report.