An illegal immigrant who acted as 'gardener' at a large cannabis factory in a Norwich suburb has been jailed for 14 months.

Elmas Germizi told Norwich Crown Court he had borrowed £12,000 to get to the United Kingdom, and when he arrived was made to work off his debt at the factory at Three Corner Avenue.

The police discovered the "large-scale, professional cannabis grow" at the semi detached home in the suburbs after a passing sergeant's suspicions were raised in May.

He noticed the upstairs windows were open despite it being a chilly day, and using a thermal imaging camera found a large heat source in the roof, said prosecutor Chris Youell.

"Other officers attended and knocked on the door but there was no response," he said. "They could see a man inside who wasn't particularly responsive."

When police forced entry they found something had been blocking the front door, and found Germizi inside, who had smashed his phone.

Four rooms of the house had been given over for growing, with 196 plants, ventilation and lighting equipment.

It would have generated around 8kg of cannabis.

The electricity had also been bypassed, but Germizi denied any knowledge of this.

"It was clearly a commercial operation," said Mr Youell.

Germizi, 24, said in interview he was a gardener at the property, and admitted being concerned in the production of a Class B drug in court.

"In the absence of any evidence to the contrary, the most police could come up with is a fingerprint on a can of Stella Artois," said Mr Youell. "It isn't really evidence of a major drug producer living the high life."

Germizi, of Willingdon Road, Eastbourne, has no previous convictions and has now applied for asylum in the UK as he fears the consequences of his remaining debts in Albania.

Andrew Oliver, mitigating for Germizi, said when he arrived in the UK he was taken to the property in Norwich and told to "turn the lights on and off".

"He accepts he came here illegally but was not aware he was going to have to commit a criminal offence when he got here," he added. "He is somewhat naive and able to be coerced into committing this offence."

Judge Andrew Shaw told Germizi destroying his phone was "an attempt to conceal of dispose of evidence".

But he added: "There is a degree to which those who raise money to come here illegally end up owing a debt," saying it makes them "vulnerable and easily susceptible".