Officers from Hampshire Police discovered more than 330 illegal plants when they raided the three-storey terrace house in Devonshire Square, Southsea, after receiving an anonymous tip-off.

A man dialled 999 at about 6pm on Wednesday and claimed three men were trying to break into the property, before hanging up.

Police were able to trace the call to a phone box in east London but are still trying to track the anonymous caller.

A team of at least 11 officers who descended on the house found no signs of a break-in on their arrival.

But after forcing their way in they discovered the cannabis plants growing in four rooms on the second and third floors, along with special high-powered lighting equipment used to cultivate the class C drug.

Police stood guard outside the property until 9am yesterday morning while scenes of crime officers worked at the scene.

The drugs have been removed for tests and the property has been sealed.

Mum-of-seven Julie Davies, 40, who lives in nearby Chestnut Avenue, Southsea, said: 'I heard sirens and then my son Guy came home and said there were police cars all over the road and that some had smashed a door in.

'There were police coming and going all night.

'It's worrying because a lot of children live round here. It's awful to think drugs were being grown round the corner.

'It's shocking to find out that something like this is going on on your doorstep.'

Hampshire Police spokeswoman Liz Harding said: 'This kind of activity will not be tolerated. We will take robust action against anyone involved with illegal drugs.

'Anyone who has any suspicions that drugs are being grown or dealt near where they live should contact the police immediately.

A 29-year-old man was arrested at the scene on suspicion of possessing and cultivating cannabis. He has been bailed to appear before Portsmouth Magistrates on October 22.