Five men have been convicted of helping operate the largest cannabis factory discovered in Leicester.

Police found 4,400 cannabis plants, and remnants of 1,500 already harvested, when they raided the disused Sky Fashions hosiery factory, Cyprus Road, Saffron Lane, in Leicester. It was enough to provide 300 kilos of the class B drug – worth £1.7 million on the streets – with similar harvests potentially available every eight weeks.

The discovery was made after a member of the public reported a suspected burglary taking place on September 28.

Following a trial at Leicester Crown Court, four Chinese men, Jian Chen, 27, Zhi Lin, 28, Ming Fen Wu, 37, and Xiao Chen, 30, who lived in the factory working as gardeners, were each found guilty by a jury of producing cannabis.

The factory's leaseholder, Mohammad Khan, 54, of St Paul's Avenue, Willesden, London, was more involved in the organisation.

He claimed to have no knowledge of the activities in the premises, but was convicted of being concerned in producing the drug, abstracting thousands of pounds worth of electricity, and concealing criminal property.

The four gardeners elected not to give evidence during the trial, although defence counsel claimed they had turned up expecting to be given legitimate shift work.

Adrian Harris, prosecuting, said the police on realising it was a cannabis factory put a cordon around the building, and rounded up seven cannabis workers, three of whom pleaded guilty.

Officers found a "large and sophisticated" cannabis factory had been set up with living accommodation for the "gardeners".

Inquiries led to the arrest of Khan who arranged to lease the premises and pay for the running costs of the business.

The defendants were remanded into custody to await sentencing on August 31, along with the three who admitted the charge at an earlier stage, Huong Dinh Nguyen, 26, Ding Hong Tran, 27, and Hong Thi Le, 19.

Det Con Nicole Main, one of the officers in the investigation, said: "This is the largest cannabis factory ever found in the city and county.

"It was a large scale, highly organised operation that was labour intensive and required people to be on site for 24 hours a day to tend to the plants.

"Local communities can play a vital part in helping us to combat the cultivation and sale of drugs by reporting any suspicious activity to the police."

Det Con Rob Buckley said outside court: "It's a fantastic result and all down to the member of the public who phoned in.

"There was a fast response from the officers who got to the scene in time to detain the culprits, who tried to flee."