The fire broke out at The Admiralty pub shortly before 5.50pm on Tuesday, and huge plumes of smoke could be seen billowing from the building.

Around 10 fire engines and 70 firefighters were originally called to the scene, but this was later increased to 20 fire engines and around 125 firefighters amid “arduous” conditions.

The London Fire Brigade (LFB) said half of the pub’s basement was alight but said it had brought the fire under control by 10pm.

Station commander Keith McDermott, who was at the scene, earlier said: “Due to the arduous, challenging and hot conditions inside the basement we’ve increased the number of fire engines and firefighters at the scene. Around 150 people evacuated the pub and surrounding businesses before the brigade arrived.”

There were no reports of any injuries and the cause of the fire is being investigated. McDermott had warned of heavy traffic disruption and asked people to avoid the area if possible.

The Fire Brigade gave an update on Twitter around three hours after firefighters began battling the flames.

A spokesperson said “Steady progress is being made at the Trafalgar Square pub fire. We’re likely to be at the scene for hours to come. It’s a hot night so crews are taking on a lot of water. Please spare a thought for all firefighters dealing with fires in these conditions.”