French Foreign Minister Dominique de Villepin said the killing "amplifies the cycle of violence."

De Villepin urged Palestinians and Israelis to recommit to the peace process that is jointly endorsed by the United States, Russia, the European Union and the United Nations and foresees a Palestinian state alongside Israel. Yassin's Hamas opposes that effort and is committed to destroying the Jewish state and replacing it with an Islamic one.

Danish Foreign Minister Per Stig Moeller said the EU has long opposed "extra-judicial killings."

He said that reviving the peace process will not be any "easier when you have killings like that going on in Gaza. Terror and violence is not the way ahead."

Norwegian Foreign Minister Jan Petersen urged both sides to curtail violence and implement the U.S.-backed "road map" plan for Mideast peace.

"This act will contribute to increased tensions in the area and will make it more difficult to implement the road map for peace and a possible Israeli withdrawal from Gaza," he said.