The identities of EU citizens were stolen by the assassins
EU foreign ministers in Brussels have "strongly condemned" the use of forged European passports in the assassination of Hamas commander Mahmoud al-Mabhouh.
The statement made no direct reference to Israel, whose secret services are widely accused of having carried out last month's killing in Dubai.
Israeli Foreign Minister Avigdor Lieberman met some foreign ministers on the sidelines of the meeting.
Mr Lieberman has reiterated there is "no proof" of Israel's involvement.
"There is no proof Israel is involved in this affair, and if somebody had presented any proof, aside from press stories, we would have reacted," Mr Lieberman said in a statement from his office.
"But since there are no concrete elements, there is no need to react."
His comments followed the EU statement which said: "The killing of Mahmoud al-Mabhouh in Dubai raises issues which are profoundly disturbing.
"We strongly condemn the use of fraudulent EU member states' passports and credit cards acquired through the theft of EU citizens' identities."
French President Nicolas Sarkozy also "unreservedly condemned" the assassination during a press conference with Palestinian leader Mahmoud Abbas, news agency AFP said.
Mr Mabhouh was killed in Dubai by a team who had entered the country on assumed identities belonging to British, Irish, French and German citizens.
The foreign ministers of those countries have been questioning Mr Lieberman about Israel's role in the assassination, in private meetings on Monday.
After meeting Mr Lieberman, UK Foreign Secretary David Miliband said he had "set out for the foreign minister the seriousness of the issue as far as Britain was concerned".
"We spent most of the time talking about the issue of the fraudulent use of British passports, and the profound concern that exists not just in Britain but all over Europe about this incident," he said.
In another development on Monday, UK Foreign Office minister Chris Bryant said another two British passports had been linked to the assassination, bringing the total to eight.
Mr Mabhouh was murdered in a Dubai hotel room, police say
The EU statement did not mention it by name, but Mossad, Israel's secret service, is widely accused of being behind the killing.
The assassins, some disguised in wigs and moustaches, were filmed following Mr Mabhouh, on Dubai's extensive CCTV network.
He was killed in his hotel room and an autopsy report said he had been electrocuted and then suffocated.
It has emerged that the British citizens whose identities were stolen also hold Israeli citizenship.
Six British Israeli citizens are to be given new passports by the British embassy in Jerusalem, it was announced on Sunday.
The British embassy said it was the first step to clearing their names, which are now on an Interpol wanted list.
Police in Dubai have also indicated there could be further revelations to come about the assassination.
Some of the estimated 18-strong hit team could have entered the country using diplomatic passports, Lt Gen Dhahi Khalifan Tamim told reporters.