Ammon News - AMMONNEWS - Israel was reinforcing troops in the occupied West Bank on Saturday to step up searches for three Israeli teenagers believed to have been abducted by Palestinians, a military source said.

The disappearance of the three on Thursday as they tried to hitch a ride from a Jewish settlement where they were studying sparked a dragnet around the nearby Palestinian city of Hebron.

It has also tested ties between Israel and Palestinian President Mahmoud Abbas, already frayed by his power-sharing deal in April with Hamas Islamists hostile to the Jewish state.

Israeli soldiers arrested at least 12 Hebron area residents, including two women, according to Palestinian officials. Locals said some of those detained were involved in car businesses like repair garages - indicating that the investigation was focusing on tracking down potential means of transport for a kidnapping.

Palestinian witnesses said the troops were also confiscating video from privately owned security cameras in Hebron and had prevented around 300 residents from leaving the area.

A military source said Israel was working on the assumption that the three teenagers were abducted by Palestinians and that it had preliminary information as to the captors' identities, though the condition of the missing teenagers was unknown.

"We can't confirm if they are alive or dead. We don't know at this time," the source said.

To intensify the searches, Israel was bringing a "significant" number of fresh forces to the Hebron area, including a paratrooper brigade, the military source said.

"We need more boots on the ground to deal with this serious development. We need to be able to track them down, we need to use all of the capabilities at our hands in order to bring this to a quick end."

Palestinian militants have said in the past that they want to kidnap Israelis to win concessions from the Israeli government. More than 1,000 Palestinian prisoners were freed in 2011 in return for the release of an Israeli soldier held captive in the nearby Gaza Strip for more than five years.

A statement posted on Arabic social media on Friday said a Palestinian wing of the Iraq- and Syria-based Islamist militant group ISIL had seized the Israelis. The statement did not appear on regular ISIL websites, raising doubts as to its authenticity.

Hebron is a Hamas stronghold whose militants have at times eluded Israeli crackdowns. An Israeli soldier was killed while patrolling the city last September. The army described that as an attack by a Palestinian sniper who has yet to be captured.

Israeli Prime Minister Benjamin Netanyahu said in a statement that he held Abbas's administration responsible for the fate of the missing three. Two of them were aged 16 and the third aged 19, according to media reports.

Netanyahu called off U.S.-brokered peace talks with Abbas over his reconciliation with Hamas, which controls the Gaza Strip and waged occasional shelling wars against Israel.

Hamas officials did not comment on the missing Israelis.

One of the three holds dual U.S. citizenship, a person briefed on the investigation told Reuters. On Friday, the U.S. State Department said Israel and Abbas's administration were "working closely together" in the search with Washington's support.

"Secretary (of State John) Kerry has ... spoken to President Abbas to urge him to do everything possible to assist in the effort to find them. President Abbas assured him that he is doing so," a U.S. spokesman said.

*Reuters