Fears are rising for the fate of three Israeli teenagers who disappeared on Thursday night near the Palestinian town of Hebron, and have not been seen since.

Israel has sent more troops into the West Bank in a huge search for the trio, but a military source says it is unknown if the boys are dead or alive.

At least 12 arrests have been made in Hebron during house-to-house searches, and the Israelis are working on the assumption they have been kidnapped.

“We are at the height of an intelligence operational effort. Many forces have been scrambled here to the Judea and Samaria district, with an emphasis on Judea and Hebron. We are carrying out arrests some of which were carried out overnight,” said Israel’s Defence Minister Moshe Yaalon.

Hamas has welcomed the disappearance and praised what it called the “Hebron heroes” responsible, but it attacked the Palestinian Authorities’ help in the search as a “moral stain”. Israel’s prime minister says he holds the administration of Palestinian President Mahmoud Abbas responsible.

In the past hostages have been taken to obtain the release of Palestinian prisoners. In 2011 more than 1000 were set free in exchange for an Israeli soldier held for five years in the Gaza strip, and there have been prisoner swaps with Hezbollah in Lebanon.