Engineers believe a torrential downpour may have caused the collapse of a house.

Heating engineer Peter Batstone was woken yesterday by a crash at 2am and thought it was someone downstairs.

But when Mr Batstone, 30, looked out of the window in the morning he noticed that half of the four-storey building next door in Iffley Road, Oxford, was missing - and dialled 999.

At 6.45am, fire crews sealed off the road outside number 153, which was being converted into flats by construction firm Leadbitter for Cherwell Housing Trust, part of the Dominion Housing Group.

Structural engineers said last night they believed the building collapsed because of a rainstorm in the middle of the night.

Mr Batstone, whose house is detached from the collapsed property, said: "I heard loud noises between about 2am and 3am and I thought it was the guy downstairs.

"Then it sounded like the noises were coming from outside, but when I looked out of the window it was pitch black, so I couldn't see anything.

"But this morning I could see that the whole of one side of the house had completely gone. It must have happened gradually during the night.

"It's possible that the heavy rainfall undermined the integrity of the foundations."

Mr Batstone said the house had been empty for about three years, although squatters may have been using the building last summer.

Last night structural engineers were checking the remains of the building to check whether it was safe.

Firefighters cordoned off about 200 yards of Iffley Road while structural engineers checked the property. The road was reopened at 9am.

The fire service's Richard Bowley said: "Mr Batstone alerted us to the situation shortly before 6.45am.

"We checked to make sure no-one was in the building before ensuring the site was safe and that there would be no further collapse of building material into the road."

Construction engineers working on the house said the building project was "progressing well" until yesterday's disaster.

Ian Batchelor, from Leadbitter, said work to refurbish and extend three terraced houses at 153 to 157 Iffley Road started in April.

He said: "Works were progressing well. However, early this morning, at about 3am, a partial collapse of the rear and side wall of the building occurred.

"We believe this was as a consequence of storm damage during the exceptional weather experienced in Oxford last night.

"No-one was injured by the event and Leadbitter's structural engineers have since visited the site and declared the building to be safe.

"We are now working with Dominion to address the situation and make good the damage to the properties and to clear debris from the neighbouring gardens."

Referring to the storm damage theory, Oxford City Council's chief planner Michael Crofton Briggs said: "I have no basis upon which to disagree with their comments."

City council spokesman Shey Cobley said the project was given planning permission last May.

She said: "We have been monitoring and inspecting the work to ensure that it is in accordance with building regulations and the structural engineers' designs.

"To date we have found that all work has been in compliance. We are awaiting the outcome of an investigation by the Health and Safety Executive to confirm the cause of the collapse."

Nicholas Yeeles, chief executive of Cherwell Housing Trust, said: "This is a very unfortunate incident, but we are relieved that no-one has been hurt or injured."