Police have discovered a major cannabis farm containing about 400 plants in Manchester city centre. Criminals were found to have been growing the Class B drug in almost plain sight out of a derelict building opposite the Crowne Plaza hotel, in a busy part of the city.

The discovery by Greater Manchester Police followed reports of three men arriving outside the building, at the junction of Mayes Street and Shudehill, in a transit van on 26 November between 6pm and 7pm. They then attempted to force entry using sledgehammers.

The men left and the van was spotted in the Newton Heath area at 7.10pm. A short time later, police discovered the building had been transformed into a major cannabis farm.

Detective inspector Victoria Kenyon of North Manchester division said: "We are determined to rid our communities of all drugs but we cannot do this alone and we need the public's support to continue to provide us with information about illegal activity in their neighbourhood. I would like assure people that we will continue to work to close in on people producing or selling drugs in Manchester."

It is not known how long the cannabis farm had been operating for and police are appealing for anyone who has information about the van or the cannabis plants to come forward. The van has a registration MA05 ONL on false plates. Anyone with information is asked to call police on 0161 856 2992, 101, or the independent charity, Crimestoppers, on 0800 555 111.