Detectives have promised to pursue a bomb hoaxer who brought Brighton to a standstill.

Two main roads in the city centre were cordoned off after a note was found in an office block saying there was an explosive device in the building.

The Lloyds TSB offices in Gloucester Place had been tampered with and an imitation bomb left inside at 8.30am yesterday.

Gloucester Place and Grand Parade were closed soon after police were alerted. The cordon was extended to cover an area from St Peter's Church to the southern edge of Victoria Gardens.

Army bomb disposal experts were called to investigate. They were joined by police search teams before the four-storey office block was declared safe at 12.20pm.

The alert caused severe traffic jams throughout the morning.

Police later apologised to drivers and thanked them for their patience, but said they had no choice but to take the threat seriously.

Chief Inspector Stuart Harrison, of Brighton and Hove police, said whoever was responsible could face up to five years in prison.

Anybody with information should contact Brighton and Hove CID on 0845 6070999.