Police sniffer dogs have got nothing on Pc Martin Brock who 'nose' a cannabis factory when he smells one.

Pc Brock was cycling through Greater Leys in Oxford on a routine patrol just before lunchtime yesterday when he recognised the suspicious whiff of drugs in the air.

After peddling back past the same spot in Redwood Close a second time with colleague Pc David Roberts-Ablett, Pc Brock identified the smell as cannabis wafting from a house.

The officers knocked on the door and searched the house, discovering a drugs factory in a second floor bedroom.

Police seized 14 plants, which had reached up to two feet high, growing in three hydroponic trays with high-powered lights.

Pc Brock, 25, said: "We cycled into the Redwood Close and I smelt cannabis so strong it almost knocked me over.

"I turned round and asked Pc Ablett if he had smelt the same. We cycled back past, tried the same thing and smelt it straight away from the address.

"It smelt as if someone was smoking cannabis from a window but there was no one there. The smell was just hanging in the air."

The officers alerted Blackbird Leys Inspector Ian Uttley and together they searched the house finding the class C drugs at 12.45pm.

All 14 cannabis plants were confiscated but police could not confirm the estimated street value.

Tackling drugs was made number one priority for policing in Blackbird Leys in a survey of residents two months ago.

Blackbird Leys area beat officer Pc Martyn Wills praised the work of officers in discovering the stash.

He said: "We have carried out planned raids in the past but this was slightly different.

"Now we have made an arrest we are going to work in partnership with Crime and Action Nuisance Team (Canact) and Oxford City Council to seek possession of the property and antisocial behaviour orders."

He added: "The message remains: drugs will not be tolerated on Blackbird Leys and Greater Leys."

The discovery is the third raid in Blackbird Leys in the past four months.

In January seven people were arrested on suspicion of drugs offences in Columbine Gardens, Greater Leys.

Four weeks later five people were arrested after a suspected cannabis farm was uncovered by police in a tenth floor flat in Evenlode Tower in Blackbird Leys.

* Stephen Ballard, 42, of Redwood Close, Greater Leys, in Oxford was charged by police with possession of cannabis resin, possession of cannabis and cultivation of a class C drug on Tuesday. He was bailed to appear at Oxford Magistrates' Court on Friday.