By Kaamil Ahmed

JERUSALEM

The Hamas movement has closed the Erez crossing between the blockaded Gaza Strip and Israel Sunday, in response to the mysterious killing of one of the group's leaders.

Interior Ministry spokesman Iyad al-Bozum said it was part of security measures put in place after Mazen Fuqaha, a leader of the group's military wing, was shot dead by unidentified gunmen on Friday.

Israel Radio reported that Israeli forces near Gaza were put on high alert on Saturday in anticipation of Hamas retaliating to the killing.

Hamas's military wing, the Al-Qassam Brigades, said in a statement that it held Israel responsible and that "the occupation will pay a heavy price for this crime".

Palestinian political analyst Talal Awkal, told Anadolu Agency that a potential reaction from Hamas could be unconventional and take time to prepare.

"Al-Qassam has the ability to carry out an assassination of similar size and strength, against leaders of Israel," he said.

Fuqaha was released in 2011 as part of a prisoner swap that involved Israel freeing 1,027 Palestinian prisoners in exchange for the release of Israeli soldier Gilad Shalit, who was captured by Hamas in 2006.

Israel held Fuqaha responsible for directing attacks against Israelis from the occupied West Bank but he was deported to Gaza after being released from prison.