Twenty fire engines and 120 firefighters and officers have been rushed to the Mandarin Oriental hotel at Knightsbridge in central London after fire broke out at the luxury hotel.

Thick plumes of black smoke could be seen billowing into the sky from the luxury Mandarin Oriental hotel on Wednesday afternoon, reported the Telegraph.

The fire brigade said the cause of the blaze was not yet known, but confirmed 35 calls had been made to the fire engine department.

Witnesses tweeted that the area had been evacuated and that roads had been closed around the £600-a-room hotel, it stated.

Smoke from the fire could be seen for miles, reported AP. The major road in front of the hotel has been closed, causing rush-hour traffic chaos in that part of London, it stated.

London Fire Brigade said it had been informed about the fire just before 4pm (1500 GMT) and presently more than 100 firefighters were tackling the blaze at a luxury hotel.

"We've now got 20 fire engines and around 120 firefighters and officers tackling a fire on the roof of a hotel in Knightsbridge. The cause of the fire is not yet known," it added.