Israel's defence minister said Saturday that authorities believe the three teens who disappeared in the West Bank while reportedly hitchhiking are alive.

Israeli security forces have been searching the West Bank since the three students of a Jewish seminary, including an American, went missing Thursday night, amid suspicions they were kidnapped by Palestinian militants. Two of the missing are 16, while the third is 19.

Defence Minister Moshe Yaalon said Saturday that the searches continue and that troops have made arrests.

"I hope that these efforts will lead us as quickly as possible to the missing in order to rescue them alive," Yaalon said. "As long as we don't know otherwise, our working assumption is that they are alive."

Teens reportedly hitchhiking home

Earlier Saturday, a senior Israeli military official said special forces scoured the southern West Bank and that progress had been made, without elaborating. He also said Israel was working with the Palestinian Authority.

The official spoke on condition of anonymity as the operation was ongoing.

Palestinian-Israel search

Israeli soldiers detain a Palestinian man during a military campaign to search for three missing Jewish teenagers in the West Bank city of Hebron on Saturday. (Mussa Qawasma/Reuters)

Details remain scarce in the teens' disappearance. Local media reported that they were hitchhiking home to their settlements in the West Bank.

A Palestinian security official said Israeli forces detained more than a dozen people in connection to the case and are examining local security camera footage.

The Palestinian official spoke on condition of anonymity because he was not authorized to talk to journalists.

The teens' disappearance is the first serious incident to strain relations with Israel since the formation of a Palestinian unity government earlier this month led by Western-backed President Mahmoud Abbas and backed by the Islamic militant group Hamas.

The West and Israel consider Hamas a terror group because of its deadly attacks targeting civilians. Hamas ruled Gaza for seven years and despite the new unity government remains the de facto power in the territory.

Militants in Gaza fired a rocket at southern Israel early Saturday, the Israeli military said, adding that nobody was hurt in the attack. Soon after, Israel retaliated with an airstrike on "a terror activity site and a weapon storage facility" in Gaza, the military said. There were no reports of injuries.

3 claims of responsibility emerge

U.S. Secretary of State John Kerry, who brokered peace talks between Israel and the Palestinians before their collapse earlier this year, spoke with Abbas and Israeli Prime Minister Benjamin Netanyahu about the missing teenagers on Friday night.

Abbas has said security co-ordination with Israel in the West Bank, usually aimed at tracking down Islamic militants, will continue despite the formation of the unity government with Hamas.

'I hope that these efforts will lead us as quickly as possible to the missing in order to rescue them alive.' - Defence Minister Moshe Yaalon

However, Palestinian officials have rejected Netanyahu's contention that the Palestinian Authority, a self-rule government that administers 38 per cent of the West Bank, is responsible for the fate of the teens. They noted that the three went missing in an area of the West Bank that is under full Israeli control.

Three different claims of responsibility for the purported kidnapping have emerged in the West Bank, though it's not clear if any are authentic.

In one leaflet, a group portraying itself as a branch of an al-Qaeda splinter group said it kidnapped the three to avenge the killing of three fighters in a clash with Israeli security forces earlier this year. Another statement was purportedly issued by the Al Quds Brigades, the military wing of the Islamic Jihad group.

The three teens are from settlements in the West Bank, territory Israel captured from Jordan in the 1967 Mideast war and that Palestinians are demanding as part of their future state along with the Gaza Strip and east Jerusalem.

Hamas frequently calls for the abduction of Israelis, and militants have captured Israeli soldiers and civilians in the past.

The Israeli military says it has foiled multiple Palestinian kidnapping attempts in recent years and warns soldiers and civilians not to accept rides from strangers. Hitchhiking nevertheless remains common.