An 11-member hit squad, six of whom were carrying British passports, was responsible for killing a Hamas commander in his hotel room last month - a murder that has brought vows of revenge from Palestinian militants, Dubai's police chief said last night.

The details given by Lieutenant General Dhahi Khalfan Tamim are the most comprehensive accusations by Dubai authorities since the body of Mahmoud al-Mabhouh was found on 20 January in his luxury hotel room near Dubai's international airport.

Lt-Gen Tamim told reporters that the alleged assassination team comprised six British passport holders, three Irish and one each from France and Germany. But he did not directly implicate Israel, as Hamas has done. The group has accused Israel's Mossad secret service of carrying out the killing and has pledged to strike back.

Lt-Gen Tamim said it was possible that "leaders of certain countries gave orders to their intelligence agents to kill" Al-Mabhouh, one of the founders of Hamas' military wing. Israeli officials have accused him of smuggling rockets into Gaza. He said forensic tests indicate that Al-Mabhouh died of suffocation, but tests are still under way to identify other possible factors in his death.

Top Hamas figures have denied reports that Al-Mabhouh was en route to Iran, which is a major Hamas backer. But the group has not given clear reasons for his presence in Dubai.

Lt-Gen Tamim sketched out a highly organised operation in the hours before the killing. He showed a news conference surveillance video of the alleged assassination team arriving on separate flights to Dubai the day before Al-Mabhouh was found dead. The suspects checked into separate hotels. They paid for all expenses in cash and used different mobile phone cards to avoid traces, he said. At least two of the suspects watched Al-Mabhouh check in at his hotel and later booked a nearby room, Lt-Gen Tamim said. He added that there was "serious penetration into Al-Mabhouh's security prior to his arrival" in Dubai, but that it appeared he was travelling alone.

"Hamas did not tell us who he was. He was walking around alone," said Lt-Gen Tamim. "If he was such an important leader, why didn't he have people escorting him?" He said there was at least one unsuccessful attempt to break into Al-Mabhouh's hotel room. It was unclear whether he opened the door to his killers or if the room was forcibly entered.

The killing took place five hours after Al-Mabhouh arrived at the hotel and all 11 suspects were out of the United Arab Emirates within 19 hours of their arrivals, he added. The police chief said the suspects left evidence, but declined to elaborate. He urged the countries linked to the alleged killers to co-operate.

Earlier this month, Hamas said it launched floating explosives into the Mediterranean to drift toward Israeli beaches to avenge Al-Mabhouh's death.

A Hamas statement last month acknowledged Al-Mabhouh was involved in the kidnapping and killing of two Israeli soldiers in 1989 and said he was still playing a "continuous role in supporting his brothers in the resistance".

More than 2,000 mourners attended Al-Mabhouh's funeral at the Palestinian refugee camp of Yarmouk, near Damascus in Syria.