College bosses have vowed to open for business as usual despite a massive fire which swept through the roof of the building.

More than 100 firefighters battled for five hours to bring the blaze at Ealing and West London College under control on Monday.

A full investigation is underway after the fire desroyed the roof and damaged other two floors of the buidling in Ealing Green. A fire service spokesman confirmed they were not ruling out arson.

The century-old listed building was open to summer school students when the fire broke out, at about 11.07am, and more than 50 students and staff were evacuated.

Gary Donald, London Fire Service borough commander for Hounslow, said: "It is too early to say what caused the fire but the hot weather made it difficult for the fire crews.

"The heat added to the problem of containing the fire as the firefighters were getting more tired than usual and their breathing apparatuses were being used up more quickly."

More than 20 fire appliances from across the capital were drafted in to help tackle the blaze so that fire crews were relieved regularly to cope with the excessive heat.

The Salvation Army set up a special mobile unit to provide food and water to the exhausted firefighters and cases of bottled water were drafted in.

A spokesman for Ealing and West London College said: "It is with regret that we can confirm that a fire took place at our Ealing Green site on Monday. The fire appeared to have started in the roof at the front of the listed building.

"Thankfully no one was injured; staff and summer school students working in the college at the time were evacuated to another area of the college."

Eye witnesses reported seeing huge flames from the roof of the college. Ciaran Markey, 16, of North Kensington, was asleep in the college grounds after attending a job interview when he was ushered out by firemen.

He said: "I was woken up by a fireman at about 11.30am. All I could see was huge flames and part of the roof had collapsed. There were loads of people running out of the building."

The whole roof of the college was destroyed, half of the third floor and 23 per cent of the second floor. Crews remained at the site overnight as the roof was still not secure and there was a concern about the tall chimneys.

Bosses at Ealing and West London College plan to re-open at the start of the new school term in September.

A spokesman confirmed: "We fully intend to provide 'business as usual' at our Ealing Green site and students should not be put off by the outward appearances.

"The extent of the damage is limited to a relatively small area which will not affect any classes."

Summer school students have been transferred to another site.