Israeli forces detained about 80 Palestinians in the occupied West Bank on Sunday as part of efforts to find three abducted Israeli teenagers, the military said.
The two 16-year-olds and a third man aged 19 disappeared on Thursday night in the West Bank, where they were seminary students in a Jewish settlement.
Prime Minister Benjamin Netanyahu, who has been overseeing Israeli security efforts from military headquarters in Tel Aviv, said they had been abducted "by a terrorist organization". There has been no public claim of responsibility.
Since the three went missing, the Israeli army has carried out house-to-house searches, round-ups and interrogations in the nearby Palestinian city of Hebron and outlying villages.
In a statement, the military said that as part of the "effort to return the three abducted Israeli teenagers approximately 80 Palestinian suspects were detained in a widespread overnight operation".
Palestinian officials put the number of people taken into custody so far by Israeli authorities at more than 100 and said they included at least seven Hamas members of the Palestinian parliament and several prisoners recently released by Israel.
Despite the broad scope of the search, few details of what is known have been made public. Israel identified the teenagers as Eyal Yifrach, Gil-ad Sha'er and Naftali Frankel, who also holds US citizenship.
The incident tests ties between Israel and Palestinian President Mahmoud Abbas, which were frayed by his power-sharing deal in April with Hamas Islamists hostile to the Jewish state.
Netanyahu planned to convene his weekly cabinet meeting on Sunday in the military compound in Tel Aviv.
Palestinian militants have said they want to kidnap Israelis to win concessions from the Israeli government, and the current incident coincides with a hunger strike by some 300 Palestinian prisoners protesting against detention without trial.
More than 1,000 Palestinian prisoners were freed in 2011 in exchange for the release of Gilad Shalit, an Israeli soldier held captive in the nearby Gaza Strip for more than five years.
In a televised statement on Saturday, Netanyahu accused Abbas's alliance with Hamas of having emboldened Palestinian militants and demanded the Palestinian leader do "all that is necessary" to resolve the crisis.
Security coordination between Israel and Abbas' Palestinian Authority in the West Bank has been close in recent years, despite the diplomatic impasse, and at US urging Abbas was working with Israel in the search.
Palestinian security officials said they were helping Israeli counterparts. Hamas condemned that cooperation.
Israeli Foreign Minister Avigdor Lieberman appeared to oppose any possible deal under which Palestinian prisoners might be traded for the three seminary students. Israel's parliament is already considering legislation that would enable judges to declare Palestinians convicted of killing Israelis ineligible for pardons.
"As far as I'm concerned, there will not be any more releases of Palestinian terrorists sitting in Israeli jails. Not as a (goodwill) gesture, and not in any other way," he told Army Radio.