A landmark building in London's West End has caught fire, sending thick plumes of smoke rising over the heart of the capital.

Fifteen fire engines and about 75 firefighters were sent just after 11am on Tuesday to tackle the large blaze on top of Marconi House, at the junction of the Strand and Aldwych.

London Fire Brigade said the fire took hold of about a quarter of the 1,076sq ft roof of the 10-storey building, which is currently being converted to a five-star hotel and 86 luxury flats to a design by Norman Foster's architectural firm.

There were no reports of people trapped or injured, and the cause of the blaze is unknown.

London Ambulance Service sent paramedics and five specialist hazardous area response team units as a precaution.

The fire caused major disruption to buses and cars in the area, with Transport for London closing parts of the Strand, the Mall and Waterloo Bridge and putting in place diversions.

The Strand, which runs between Trafalgar Square and Fleet Street, includes Charing Cross railway station, Somerset House, the Royal Courts of Justice and several West End theatres.

London Fire Brigade station manager Tom Goodall said: "Crews are working really hard in hot and taxing conditions to bring this fire under control.

"There is a lot of smoke in the local area and we are asking people to keep their windows closed.

"The building, which is under refurbishment, was evacuated quickly and there are no reports of any injuries."