Dubai has accused Israel of being behind the assassination, but the Israeli foreign minister has said there was no proof his country carried out the killing.

"The UAE has identified two British suspects holding British travel documents and as part of the ongoing investigation has shared the information with the British government," the source in the UAE told Reuters.

Two more suspects in the killing of Mabhouh in a hotel in January were identified as holding Irish passports, the source added.

The Dubai authorities last week released the identities of 11 people who traveled on forged British, Irish, French and German passports to kill Mabhouh, and said that two Palestinians suspected of providing logistical support were in custody.

The new information brings the tally of fake British passports used to eight and Irish identities used to five.

Six people previously identified by Dubai as members of the hit squad are Britons living in Israel. They deny involvement and say their identities were stolen.

Officials have said at least 18 people may have been involved in the assassination.

Mabhouh, who was born in the Gaza Strip but had lived in Syria since 1989, was killed in his hotel room on Jan. 19, a day after he arrived in Dubai.

He was suffocated, the source in the UAE told Reuters on Tuesday, but the authorities were awaiting results of additional tests.

Hamas has said Mabhouh was involved in smuggling weapons from Iran to the Gaza Strip.

In a short statement on Monday that European diplomats said was intended to put pressure on Israel, EU foreign ministers said that the assassination was "profoundly disturbing" and that its citizens' rights were violated.

Dubai police have said they are virtually certain that Israeli intelligence agency Mossad carried out the killing, and United Arab Emirates Foreign Minister Sheikh Abdullah bin Zayed vowed on Sunday to bring those responsible to justice.

Mabhouh's killing was the third high profile murder in less than two years in the regional trade and tourism hub Dubai, one of seven emirates in the UAE federation, where violent crime is rare.

Meanwhile, the Gulf Cooperation Council denounced on Monday as a "terrorist act" the assassination of a Hamas leader in Dubai and called for firm action against those responsible.

GCC Secretary-General Abdul Rahman Al-Attiya called in a statement for EU countries to cooperate with the United Arab Emirates' investigation into the killing, "to bring the perpetrators of this crime to justice and prevent the repeat of such a terrorist act."

Dubai police chief Lt. Gen. Dahi Khalfan has said he is "99 if not 100" percent sure Israeli intelligence service Mossad is behind the killing.

"The states whose sovereignty and the security of their citizens has been violated by this cowardly act should take a firm stand against the party responsible for violating international laws and norms," Attiya said.