One of Oxford's biggest hauls of cannabis plants has been discovered in a police raid on a quiet residential street.

Police believe they are now forcing most of the growers to ply their trade elsewhere.

About 20 police officers raided the end-of-terrace house in Old Road, Headington, at about 8.15am today and found 552 cannabis plants.

Three rooms were filled with mature plants ready to be harvested while two other rooms contained smaller plants.

Click here to see a gallery of pictures from the event

The estimated street value of the drugs seized was £88,000.

In the first five months of this year, 17 cannabis factories were found in Oxford.

Since May, only three have been discovered.

Pc Leigh Thompson, drugs coordinator for Oxfordshire, said: "This is the largest raid in Oxford that I can recall - and the highest number of plants seized from one location.

"There was a problem with these type of premises in Slough, then Reading and on to Oxford.

"Now there seem to be a lot in Milton Keynes."

He said fewer cannabis factories were cropping up in Oxford.

"It seems they move in, do what they do until it gets a little bit too hot, then move on somewhere new."

Police officers were accompanied by staff from Southern Electric, following suspicions that electricity was being illegally taken from the National Grid.

Scenes-of-crime officers and forensics teams were called to the house and the plants were removed.

No-one was inside the house when officers forced their way in.

Pc Charlie Ellis, who led the raid, said: "This clearly will impact on the people running these drugs factories. But it is an ongoing battle against these guys.

"It has definitely got quieter in the last few months. At the start of the year, it felt like there was a warrant every other week."

Neighbours said the house used to be rented by students but had been empty in recent months.

A 39-year-old woman, who did not want to be named, said: "It doesn't surprise me in the least.

"When it was re-let, the first thing they did was block out the windows. Every once in a while, someone would pull up and walk out with shopping bags filled up with something.

"It's a bit scary. I was more worried about a fire at the house than anything else, but I am pleased because I hate drugs."

A 73-year-old neighbour said: "There has been an awful lot of these found this year - you wonder where next.

"What can you do apart from have the police come round and close it down? I don't think they'll ever stop them completely."

One pensioner said: "I had some kind of inkling something was going on because it is an empty house, no-one ever lives there but people often come and go."

Anyone with information should call police on 08458 505505 or speak anonymously to Crimestoppers on 0800 555111.

Cannabis factories first appeared in Oxford in early 2006 and since then, a string of them have been raided across the city.

It is believed many have been run by organised criminal gangs - with the potential street value of drugs seized running to many hundreds of thousands of pounds.

In many cases, growers illegally tamper with mains electricity supplies to power the lamps required to grow the plants - posing a serious safety risk to neighbouring homes.

Many houses raided have had windows covered with sheets to stop people from being able to see in - and to assist with growing.

Most of the factories raided have used a hydroponic set-up to produce cannabis - with plants grown in water, using nutrients rather than soil.