In a short statement that European diplomats said was intended as a rebuke to Israel, EU foreign ministers said that the assassination was "profoundly disturbing" and that its citizens' rights were violated.
Dubai has accused Israel of being behind the killing of Hamas commander Mahmoud al-Mabhouh. Israel has not denied or confirmed it played any role but its foreign minister, visiting Brussels, said there was nothing to link it to the killing.
"The EU strongly condemns the fact that those involved in this action [the killing] used fraudulent EU member states' passports and credit cards acquired through the theft of EU citizens' identities," ministers said after talks in Brussels.
"The EU welcomes the investigation by the Dubai authorities and calls on all countries to cooperate with it."
Diplomats said the statement was intended to put pressure on Israel, but no direct reference was made to it because there was no proof Israeli agents carried out the assassination.
The declaration is unlikely to have any long-term repercussions for EU-Israeli ties and Israeli officials have played down the possibility of a full-blown crisis.
Sami Abu Zuhri, a spokesman for the Hamas militant group in the Gaza Strip, said the EU statement lacked teeth and would tempt Israel to carry out "more crimes of this kind".
"Condemning the use of [European] passports was insufficient. The statement did not indicate any condemnation of the crime: Mabhouh's assassination," he said.
French outrage, British concern
Dubai authorities say they are virtually certain Israeli agents carried out the killing and have released the identities of 11 people who travelled on forged British, Irish, French and German passports to kill Mabhouh in a hotel.
Mabhouh was involved in smuggling weapons from Iran to the Gaza Strip, Hamas has said.
France and Germany have asked Israel for an explanation and President Nicolas Sarkozy spoke of France's "irrevocable condemnation of what is nothing less than an assassination" after talks with Palestinian President Mahmoud Abbas in Paris.
Prosecutors in Cologne are looking into whether one of the men acquired a German passport under a false pretext to engage in spying, and could refer the case to federal prosecutors for investigation, a spokesman said.
Six Britons with the same names as members of the alleged hit team live in Israel and say their identities were stolen.
Lieberman: You watch too many James Bond movies
British Foreign Secretary David Miliband urged Israeli Foreign Minister Avigdor Lieberman to cooperate with a British inquiry into whether British passports could have been forged for use by the assassins.
Lieberman, who met Miliband in Brussels, said in a statement there was no proof Israel was involved in the killing, and later told reporters: "I think you have all seen too many James Bond movies."
(EurActiv with Reuters.)
