An image grab taken on February 16 from hotel surveillance camera footage, released by Dubai police. CCTV footage showed the agents were present for just 22 minutes. Image Credit: Supplied

London: The hit squad behind the assassination of a Hamas commander in a Dubai hotel tried to make his death look like an accident by electrocuting him with a bedside lamp.

Police sources said the killers tried to "induce the effects of a heart attack" before smothering Mahmoud Al Mabhouh with a pillow in his room.

It is understood that the lamp was taken apart and the wiring attached to a device that pulsed electricity into his body.

A source said there were burn marks on his chest from an electric shock but added that because CCTV footage showed the agents were there for just 22 minutes, the investigators believed the electric current was not used to torture him.

An electric shock can make the heart muscles go into spasm, just as they would if a victim suffered from a heart attack brought on by high blood pressure.

Police said they found pills used to treat high blood pressure in Al Mabhouh's room.

When he was discovered by a cleaner and member of security at lunchtime the day after his murder, he was wearing only a pair of black shorts under the bed sheets. A later post-mortem showed that he had been killed by suffocation but "without the need for violence".

The 18-person team waited for Al Mabhouh — who was travelling under a fake name — before tracking him down to the hotel.

The killers had planted a tracker device in his rented Toyota Land Cruiser and tailed him to his hotel.

In the few hours before his death, Al Mabhouh made a visit to Dubai Mall where he bought a pair of shoes. He returned to his room at 8.24pm and his killers were in place. It is believed that he was overpowered by four men shortly afterwards when he answered the door.