Emmad Qureshi, 26, was killed in the blast in Stanley Road, Harrow, north London, on May 7.

His body was found in rubble after the explosion, which is believed to have originated in the house next door.

A 26-year-old man suffered head and armed injuries in the blast and a 17-year-old girl was left with serious burns. They are both still in hospital.

Police now believe the teenager, named in reports as Charlotte Anderson, could have been the target of the attack.

She complained about two teenage girls outside her flat on the morning of the explosion.

A Scotland Yard spokesman said a purple liquid which smelled of rotten eggs was poured through her letterbox between 9 and 11am that day.

The explosion ripped through a number of houses shortly after 9.30pm.

Officers will send in experts to identify the liquid once they can access the blast site.

That will not happen before next week, when police will sift through large amounts of rubble for evidence.