The Christchurch bus exchange was evacuated last night after a woman claimed she had a bomb.

Canterbury Senior Sergeant Roy Appley said the building was briefly evacuated and although a bag was found, there were no explosives in it.

Police were called to the Lichfield St bus exchange about 9.15pm and a woman has been arrested after she claimed that she had thrown a bag containing a bomb into the bus exchange.

She has been charged with possession of offensive weapon and causing alarm to persons inside the building, Appley said.