"Shaikh Yasin's blood will not have been shed in vain - we call on all the Abu Hafs al-Masri Brigades to avenge the shaikh of the Palestinian resistance by striking the tyrant of the century, America, and its allies," said the statement carried by the www.al-ansar.biz website.


The Abu Hafs al-Masri Brigades take their name from an al-Qaida leader killed in Washington's 2001 war in Afghanistan and is a name regularly used in communiques from the Islamist network to its cells around the world.


There was no immediate way of establishing the authenticity of the latest statement.


White House


Meanwhile, the White House said on Monday it was "deeply troubled" by Israel's assassination of Shaikh Yasin.


"We are deeply troubled by this morning's actions in Gaza," White House Scott McClellan said.


Earlier, the Bush administration said it had no advance intimation about Israel's plan.