Two boys have been arrested on suspicion of arson in connection with a huge fire at Britain's largest mosque in south London on Saturday.

A 16-year-old and a 14-year-old have been held for questioning over the fire at the Baitul Futuh mosque in Morden, a spokeswoman for Scotland Yard has said.

The blaze began at around midday and was tackled by 70 firefighters.

According to the London Fire Brigade, the fire was confined to an administration building and the mosque itself was undamaged.

There were few worshippers in the mosque at the time of the fire but one man was taken to hospital for smoke inhalation.

The fire is believed to have damaged half of the building's ground floor.

The mosque was built for the Ahmadiyya Muslim community, an Islamic sect founded in India in the late 19th century, and bears the sect's motto "Love is for all, hatred is for none."

It is the largest mosque in Western Europe and can house up to 10,000 worshippers.

About half of the mosque's ground floor was reported to be on fire (@Doggy_Boutique)

Local councillor Imran Udding, whose ward includes the mosque, told the Evening Standard: "The really important thing to note is that the blaze took hold really quickly, but the hall where it started was also evacuated very quickly.

"We need to investigate what happened here. The mosque is very popular in the area. It has a very positive impact. It does a lot of community work."

He said it "could have been a lot worse" if the fire had struck a day earlier when the mosque was full of worshippers celebrating Eid.