Anti-terrorist security was stepped up in Sussex today in the wake of last night's bombing of MI6 headquarters in London.

Police gearing up for next week's Labour Party conference in Brighton launched a series of vehicle checks throughout Sussex.

Senior officers are taking the threat of a bombing seriously and are apologising in advance for the disruption to traffic the new measures will bring.

The MI6 building - headquarters of Britain's Secret Intelligence Service - was rocked by an explosion from a small missile last night.

Dissident Republican terrorists were thought to be behind the attack.

Tight security is already in place around the Brighton conference centre to prevent a repeat of the IRA's bombing of the Grand Hotel in 1984, when five people died and 30 were injured.

It includes a ring of fences surrounding the centre and neighbouring hotels.

Police reinforcements have been brought in from London, Hampshire and Surrey, and a fixed-wing aircraft from Hampshire has been made available.

Sussex Assistant Chief Constable Nigel Yeo said: "Our security operation for the conference has been many months in the planning but it has a built-in flexibility to enable us to adjust our level of response, according to the security threat.

"Clearly, we cannot ignore the implications of last night's incident in London.

"Among other measures, people locally will see an increase in the number of police road checks, not just in Brighton, but across Sussex.

"We are sorry if this causes inconvenience and disruption but I am sure people will understand the need."