Three Israeli teenager settlers have gone missing in the occupied West Bank with Prime Minister Benjamin Netanyahu saying he held the Palestinian leadership responsible for their safety.
"The IDF (Israeli military) confirms three teenagers are currently missing," an army statement said.
"The individuals were last seen late last night in the area of Gush Etzion," it said, referring to the main settlement bloc in the southern West Bank.
The army gave no further details and refused to say whether the three had been kidnapped.
"We do not give details that could hamper the investigation," a spokesman said, adding only that a "large scale" search was under way.
Israeli media speculated the three may have been kidnapped by Palestinians.
One has US citizenship, and the American embassy has been informed, public radio said.
Mr Netanyahu's office said it held the Palestinian leadership responsible for their disappearance.
"Israel holds the Palestinian Authority responsible for the wellbeing of the three missing Israeli teens," spokesman Ofir Gendelman wrote on Twitter.
> Israel holds the Palestinian Authority responsible for the well-being of the three missing teenagers.— PM of Israel (@IsraeliPM) June 13, 2014
General Adnan al-Damiri, spokesman for the Palestinian Authority's security services, described Netanyahu's remarks as "mad".
He said the PA had no authority in Gush Etzion area, a settlement bloc under total Israeli civilian and military control.
"Even if there was an earthquake, Mr Netanyahu would blame the Palestinian Authority," he told AFP.
The Ezzedine al-Qassam Brigades, the armed branch of the Islamist Hamas movement which until June 2 governed the Gaza Strip, issued a statement warning that "the occupier will never have security" but did not refer specifically to the missing teens.
Mr Netanyahu's bureau said he had spoken by telephone to US Secretary of State John Kerry, telling him he held Palestinian president Mahmud Abbas responsible for the fate of the three.
Last week, a new Palestinian unity government of independents backed by Hamas was sworn in, prompting a furious response from Mr Netanyahu's government. Hamas's charter calls for the destruction of Israel.
"What is happening on the ground since Hamas joined the Palestinian government is destructive. It all results from the entry into government of a terrorist organisation," Mr Netanyahu said.
Mr Kerry also telephoned Mr Abbas, an official Palestinian source said.
Israeli troops set up checkpoints in Gush Etzion and around the southern city of Hebron on Friday to stop and search cars, an AFP correspondent said.
Another Palestinian official said the security services were "cooperating" with Israel to gather information on the teenagers' disappearance.
Military radio said they were students at a Jewish seminary and went missing late Thursday near a bus stop.
The army was carrying out searches in Dura, a town southeast of Hebron, an AFP photographer said.
Public radio said Mr Netanyahu had been in touch with the teens' families to reassure them that "everything" was being done to find them.