Jerusalem (AFP) - Israeli Prime Minister Benjamin Netanyahu demanded Palestinian president Mahmud Abbas's help Monday in securing the release of three kidnapped teenagers, as the army launched a massive crackdown on Islamist movement Hamas.
Netanyahu's phone call to Abbas was their first direct political contact since 2012, and took place as Israel carried out a vast search operation in the West Bank to find the three youths, whom the Israeli premier said were kidnapped by Hamas militants last week.
As the manhunt entered its fourth day, Israeli troops arrested scores of Hamas members, among them MPs and former ministers, bringing the total number of Palestinians rounded up since Friday to 150, the biggest sweep in the territories in years.
"I expect you to help in the return of the kidnapped youths and the capture of the kidnappers," Netanyahu told Abbas.
"The Hamas kidnappers went out from territory controlled by the Palestinian Authority and returned to territory controlled by the Palestinian Authority," he said.
So far, there has been no formal claim of responsibility, and Hamas has dismissed Israel's accusations as "stupid".
Abbas's office issued a statement condemning "the kidnapping of three Israeli youths".
But it also denounced Israel's "raids on Palestinian homes" and arrests of "many innocents" during which a 19-year-old Palestinian was killed.
Ahmad Arafat Sabarin was shot dead during clashes in Jalazoun refugee camp near Ramallah which erupted when troops arrived on an arrest mission, medics told AFP.
The missing three are Gilad Shaer, 16, from Talmon settlement near Ramallah, Naftali Frenkel, 16, from Nof Ayalon, and Eyal Ifrach, 19, from Elad, both in central Israel.
The United States has offered "assistance to try and find the kidnapped teenagers as swiftly as possible and return them unharmed to their families," State Department spokeswoman Jen Psaki said.
US officials from the consulate general in Jerusalem have been in touch with the family of one of the boys, she said, although she would not confirm if he was an American citizen.
Secretary of State John Kerry also spoke with Netanyahu about the situation on Monday.
Egypt meanwhile urged Israel to show "restraint" in its crackdown on Hamas.
Although arrests have taken place across the West Bank, troops are focusing their search on the southern city of Hebron and the surrounding area, home to some 663,000 Palestinians.
- Hamas hallmarks -
Overnight, soldiers arrested more than 40 Palestinians, the army said, including parliament speaker Aziz Dweik, who is a Hamas member.
New York-based watchdog Human Rights Watch urged Israel to refrain from "arbitrary" arrests in their search for the teenagers.
"Israeli forces should respect the laws of war with respect to the Palestinian population in the occupied territory and not carry out mass, arbitrary arrests," it said.
A Palestinian intelligence officer told AFP the kidnapping bore the hallmarks of a Hamas operation, noting the Islamist movement had a policy of keeping its captives alive in the hope of securing a prisoner exchange.
The crisis emerged 10 days after the establishment of a new Palestinian government of technocrats, the first fruits of a reconciliation deal between rival leaders in the West Bank and Gaza which has been furiously denounced by Israel.
Netanyahu convened his security cabinet late Monday to discuss possible punitive steps against Hamas, which Walla news site said might include banishing Hamas members from the West Bank to Gaza and "destroying their homes."
"This is a serious incident with serious consequences, and we will react responsibly and firmly," Netanyahu told reporters in Jerusalem.
"We need to be prepared for the possibility it will take time."
Pundits said the Netanyahu government had been presented with a "golden opportunity" to deal both a military and a diplomatic blow to its Islamist foe.
"Had Israel arrested dozens of Hamas leaders and imposed a curfew on large areas (of the West Bank) a week ago, the Palestinian Authority would have raised an outcry... Today the Palestinian Authority is silent," wrote Alex Fishman in the top-selling Yediot Aharonot newspaper.