Gaza City - After a wave of weekend suicide bombings killed 25 people in Israel, Palestinian police arrested three senior leaders of the hardline Hamas group in a crackdown that netted more than 75 Islamic militants.

A Hamas official confirmed the arrest of two of its political leaders, Ismail Abu Shanab and Ismail Haniya, and said police had issued arrest warrants for another two.

Haniya and Shanab are spokespersons for Hamas in the Gaza Strip, although the latter is an intellectual considered close to the group's ailing spiritual leader, Sheikh Ahmad Yasin.

The security source said militants from Hamas and the smaller Islamic Jihad were rounded up after Yasser Arafat's Palestinian leadership pledged to crack down after the anti-Israeli suicide attacks which left 25 Israelis dead, including many youngsters at a Jerusalem mall, and 170 wounded.

They were arrested because "the two movements are not committed to the Palestinian Authority's decision for a ceasefire" in the 14-month intifada, the security source said.

About 50 militants from both the groups had been arrested in the West Bank, and 25 Islamic Jihad members had been detained in the Gaza Strip, he said.

Most of the arrests came just hours after the leadership declared an unprecedented state of emergency and invoked sweeping powers still on the statute books from British mandate rule over Palestine between 1923 and 1948.

Israel and the international community gave Arafat an unequivocal challenge to jail hardliners to prove his commitment to a US peace initiative after the suicide bombings in Jerusalem and Haifa at the weekend.

Islamic Jihad, meanwhile, claimed two similar attacks last week which killed five Israelis, including a suicide bombing in the northern city of Pardes Hanna on Thursday that ripped apart a public bus.

Israel warned it would inflict a devastating military response if Palestinian authorities failed to conduct a wholesale roundup of Islamic militants.

Earlier in the day, Palestinian police had also tried to arrest eight Islamic militants in the northern West Bank, witnesses said.

However, they found local Hamas political leaders Jamal Abu Hejja, Ibrahim Jibr and Khaled el-Haj as well as Jihad official Besam Sedi had already taken flight after the declaration of a crackdown on the groups.

They swooped on the home of four brothers all belonging to Hamas in the Askar refugee camp in Nablus to the south, but were prevented from entering by an angry crowd of women, the witnesses said.

On Saturday, a senior Islamic Jihad leader, Mohammed al-Hindi, surrendered to police in Gaza after making a dramatic escape during a gunbattle, and at least 13 other members of the group were detained in the West Bank.

Israel soldiers swooped on the Palestinian town of Abu Dis on the edge of annexed east Jerusalem yesterday in search of two Hamas members, Nabil Halabia and Osama Bashar, suspected of being involved in the devastating triple suicide bombing in Jerusalem.

They failed to find them.

Halabia had spent five years in Israeli jails, while Bashar was a Palestinian policeman who resigned on Thursday.