Anti-terrorist road checks are being carried out in Sussex in the run-up to next week's Labour Party conference in Brighton.

Officers involved in the high-profile security operation have appealed to the public to remain vigilant.

Posters are being put up urging people to report anything suspicious to the police immediately.

Security for the conference, which runs from next Sunday until Thursday, has been stepped up in the light of recent bombings in Northern Ireland.

There are also threats from other militant groups and last night Labour forced hunt supporters within its ranks - the Leave Country Sports Alone group - to cancel a reception planned for the opening day.

Organisers are reportedly telling guests, including actors and film directors, that they will be turned away because of security risks.

Letters have been sent to 1,500 people including actor Jeremy Irons and director Lord Puttnam, asking them to join a protest on Sunday night instead.

A Labour spokesman said neither pro nor anti-hunt groups would be allowed inside the tightly guarded "island site" comprising the Brighton Centre and Grand and Metropole hotels for security reasons.

He added: "Whatever plans the fox hunting lobby had to hold a reception at the Grand they needed our agreement and it was not forthcoming.

"Both sides in this highly contentious argument have been treated equally."

Extra police from neighbouring forces have been drafted in to boost security around the so-called Island Site in Brighton, an area surrounding the Brighton Centre.

Horses are being brought in from the City of London force and an aircraft from Hampshire Police will patrol the skies.