A man arrested on suspicion of manslaughter over a fatal gas blast may have examined a boiler in one of the affected houses in the days before the disaster.
The 32-year-old, from the Shaw area of Oldham, was held in London yesterday and was being taken to Manchester today for questioning in connection with Tuesday's massive explosion.
Police said they understand the suspect may have done some maintenance work at one of the houses in Buckley Street, Oldham.
Two-year-old Jamie Heaton was killed and neighbour Andrew Partington, 27, suffered serious burns as the blast flattened their homes and damaged scores of other houses.
Jamie was killed while watching TV in his home but his mother miraculously survived after stepping out to hang out washing in the yard.
Jamie Heaton, 2, was killed in the explosion
Local reports suggest there was a problem with the boiler at Mr Partington's home in the days and weeks before the explosion.
Police have also said they are investigating reports of a row involving the injured man and his partner, mother-of-five Tanya Williamson, who left the family home with her children before the blast.
Steve Heywood, Assistant Chief Constable of Greater Manchester Police, said: "A 32-year-old man from the Oldham area was arrested in London and conveyed to Manchester today. He will be subject to a robust interview process today.
"What I would like to stress though is he is just one single line of inquiry we are pursuing. There are a number of other lines of inquiry which we are pursuing.
"I would not want you to read into it that this is actually the only line of inquiry we are pursuing."