A MASSIVE fire has broken out in a building that backs onto the grounds of the Saudi Arabian Embassy in London.

About 40 firefighters are currently trying to contain the blaze in Chesterfield, Mayfair which started shortly after 9am (local time).

The London Fire Brigade has told media that the cause of the blaze has not yet been determined, however it is affecting the extraction system of a restaurant in Curzon Street.

The fire is not at the Saudi embassy.

Witnesses have told media they had heard explosions however authorities have not confirmed these reports.

The blaze has visibly spread across four floors in the building.

A fire engine is also inside the grounds of the embassy tackling the blaze.

No injuries have been reported.

More to come