Dubai Police said Sunday that at least seven individuals were involved in the murder of a Hamas official in a local hotel last week, and would not rule out the possibility that the Israeli spy agency Mossad had a hand in the attack.

"It could be Mossad, or another party," police chief Dhahi Khalfan told AFP. "Personally, I don't exclude any possibility. I don't exclude any party that has an interest in the assassination."

Khalfan told news agencies on Sunday that the seven primary suspects carried various European passports, but he would not elaborate.

The police have contacted the relevant European nations, said a top commander, in order to glean more information on their identity.

The hit squad that assassinated top Hamas commander Mahmoud al-Mabhouh in his Dubai hotel room injected him with a drug that induced a heart attack, London newspaper The Times reported on Sunday.

A team of assassins broke into al-Mabhouh's room and killed him silently before photographing all the documents in his briefcase and left a 'do not disturb' sign on the door, said the paper quoting unnamed sources in the Middle East.

Latest theories contradict a version of events given last week by Al-Mabhouh's brother, who told Haaretz that a medical team had determined the cause of death as a massive electric shock sustained to the head. Doctors had also found evidence of strangulation, he said.

Hamas has publicly blamed Israel for the assassination, which occurred only three days after the first ever visit to the Arab Emirates by an Israeli minister.

Mahmoud al-Zahar, one of the group's leaders and co-founders, claimed Saturday in an interview with Al-Jazeera television that the killers entered Dubai on forged passports as part of the entourage of Uzi Landau, the infrastructure minister, who was attending a regional conference on renewable energy.

Landau has refuted any connection between his visit and the assassination.

The 50-year-old Hamas man's body was discovered by staff at the luxury Al Bustan Rotana hotel after lunch on January 20. There were no suspicious signs and local doctors diagnosed a heart attack.

But nine days later, blood samples sent to Paris for analysis showed signs of poison and Hamas announced his death and blamed the Israeli agents for the assassination.

Al-Mabhouh, who was the official responsible for arranging arms supplies from Iran to Gaza, was tracked from the moment he boarded Emirates flight EK 912 at Damascus at 10.05 on January 19, the Times reported.

Hamas has since accused Israel of 'breaking the rules of the game' by taking its war with Hamas onto foreign territory and vowed to retaliate by targeting Israeli officials in Europe.