The substance was put into the house about 10 hours before the property, in Harrow, north London, was levelled in a blast on Wednesday.

One man died in the explosion, while a 17-year-old girl - thought to be the likely target - remains in hospital with serious burns.

Police have officially named the dead man as 26-year-old businessman Emad Qureshi. He died as the blast ripped through a number of houses in Stanley Road.

But police said they believed the epicentre of the blast was a social housing flat, next door to Mr Qureshi. The 17-year-old who lived there had earlier called the police to complain about two teenage girls gathered outside.

After the explosion, she was pulled from the rubble of number 21 Stanley Road by neighbours. Named locally as Charlotte, she was taken to Chelsea and Westminster Hospital with severe burns.

Police were originally called after reports of a gas explosion, but engineers could find no fault with the mains supply.

Speaking at the scene of the blast, Detective Chief Inspector Colin Sutton said the terraced home could have been deliberately targeted.

Mr Sutton said: "We still haven't ruled out a gas explosion but experts say it is unlikely to be the cause.

"What we can say is that we are happy there is no link to any terrorist organisation or acts here."



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