Detectives probing the cause of the fatal South Harrow explosion have said it may have been caused by gas.

Emmad Qureshi, 26, of 23 Stanley Road, died of a wound to the neck caused by debris after number 21, next door, blew up at 9.40pm on Wednesday last week.

A 26-year-old friend of the deceased suffered head and arm injuries but was later discharged from hospital while 17-year-old Charlotte Anderson, who lived at 21, is being treated at Chelsea and Westminster Hospital, west London, for severe heat burns.

When police revealed a mysterious purple liquid had been poured through the letterbox of Ms Anderson's front door on the morning of the blast, and that she had made a 999 call around the same time, rumours circulated that she had been targeted by a gang of girls.

But in yesterday's (Thursday's) edition, the Observer warned these could be red herrings and carried comments of residents who believed gas was the trigger.

The Metropolitan Police have now said the liquid "was not a cause of, nor a contributory factor to, the explosion".

DCI Colin Sutton said: "Access was gained on Wednesday to the front of 21 Stanley Road, and several items, including the gas meter and piping, and the doormat from the house, have now been removed for scientific examination.

"Witnesses, including some young people who were outside the house during the morning of Wednesday May 7, have been traced and spoken to.

"None of the information gathered in the past few days supports the theory of explosives, or similar devices, nor a deliberate act to cause an explosion.

"Although there was no gas appliance in use at number 21, there was a supply - and a meter - which had been unused for some years.

"Preliminary indications are that a large volume of gas may have passed through the meter on May 7, and it is this which has now become the focus of our investigation, which we are conducting hand in hand with the Health & Safety Executive."

n Anyone with information on the incident is asked to call the Incident Room on 020 8247 7911; if you wish to remain anonymous please call Crimestoppers on 0800 555 111.