Hundreds of residents in tower blocks in south London are to be evacuated after an investigation revealed their homes might not be safe.

Safety fears have seen the gas supply to 242 flats in Ledbury Towers in Southwark cut off immediately following the results of an investigation, which found a gas explosion could lead the building to collapse.

Following the Grenfell fire tragedy, residents raised concerns over cracks in the buildings and structural engineers were instructed to investigate their cause, the council has said.

During the investigation, an issue was raised about the gas supply to four blocks, which was installed in the late 1960s.

In a letter to residents announcing the decision of the evacuation, the council said that in 1968 a similarly constructed tower block in Newham, the Ronan Point, collapsed after a gas explosion only two months after it opened. Three people were killed.

Following the incident, safety work was supposed to have been carried out on blocks around the UK but this may not have happened on the Ledbury estate.

Southwark Council said it appreciated the move was "inconvenient" for those living in the Peterchurch, Bromyard, Skenfirth and Sarnsfield blocks but that it was "not willing to take any risks".

Stephanie Cryan, deputy leader and cabinet member for housing at Southwark Council, said records suggest the four blocks were strengthened following the Ronan Point incident.

She said: "Arup's structural investigations suggest this strengthening may not have occurred, and we have therefore turned off the gas, until further investigations can be done.

"We are doing all we can to provide residents with alternatives while the gas is turned off, and are working up a plan to permanently replace the gas with electric ovens, boilers etc as part of the wider works, should that be necessary.

Hundreds of residents to be evacuated over gas safety fears in south L Show all 9 1 /9 Hundreds of residents to be evacuated over gas safety fears in south L Hundreds of residents to be evacuated over gas safety fears in south L Gas engineers at work outside Ledbury Towers, south London, where residents facing evacuation from high-rise London flats have said safety concerns were "ignored for decades". PA Hundreds of residents to be evacuated over gas safety fears in south L Gas engineers at work outside Ledbury Towers, south London, where residents facing evacuation from high-rise London flats have said safety concerns were "ignored for decades". PA Hundreds of residents to be evacuated over gas safety fears in south L Gas engineers at work outside Ledbury Towers, south London, where residents facing evacuation from high-rise London flats have said safety concerns were "ignored for decades". PA Hundreds of residents to be evacuated over gas safety fears in south L General view of a tower block at Ledbury Towers, south London, where hundreds of residents will be evacuated from their high-rise flats after an investigation revealed their homes may not be safe. PA Hundreds of residents to be evacuated over gas safety fears in south L An original gas pipe inside a flat in Bromyard House, on the Ledbury estate in south London. PA Hundreds of residents to be evacuated over gas safety fears in south L General view of Ledbury Towers, south London, where hundreds of residents will be evacuated from their high-rise flats after an investigation revealed their homes may not be safe. PA Hundreds of residents to be evacuated over gas safety fears in south L A shut off gas main outside Ledbury Towers, south London, where residents facing evacuation from high-rise London flats have said safety concerns were "ignored for decades". PA Hundreds of residents to be evacuated over gas safety fears in south L Labour MP for Camberwell and Peckham, Harriet Harman speaking to the media outside Ledbury Towers PA Hundreds of residents to be evacuated over gas safety fears in south L General view of Ledbury Towers, south London, where residents facing evacuation from high-rise London flats have said safety concerns were "ignored for decades". PRESS ASSOCIATION Photo. PA

"We have also written to the Department of Communities and Local Government to inform them of this issue, as it may well have implications for other blocks around the country that were constructed in this way."

In the letter sent to residents, the council said it hoped people would be allowed to remain in their homes while the work to fix the cracks was carried out.

"But this new information means we are now planning to temporarily decant the blocks over the coming weeks and months," the letter added.

The council said there was no plans to evacuate residents immediately or over the coming weeks but that if the process to sort alternative power for the buildings takes too long they may need to offer alternative accommodation.

Hot plates will be provided temporarily to residents so they can prepare meals and single electric water heaters should be installed in every flat.