A dog owner fears he could be blackmailed into paying a ransom to recover his pet after it was pinched by a pair of dog-nappers.

Ron Collins, of Ingram Road, East Finchley, had his five-year-old bullmastiff stolen from outside his home on Sunday, at about 6.30pm.

He was painting windows when he noticed two men talking to the dog, one of whom was carrying a lead. They walked off, but CCTV footage from Mr Collins' home showed them return a few minutes later and coax the pedigree pooch towards High Road and East Finchley Tube station.

"I feel totally gutted. It was a very blatant crime and had absolutely amazing front about it," said Mr Collins, who has put up lost dog posters around the area.

"They knew the dog was there and approached the whole theft as though they were professionals. They knew what they were doing.

"Until someone comes forward, I don't know what I am up against. If someone is being genuine and finds the dog they won't want a reward, but I don't know how these people will treat the situation."

Police are investigating the incident and are appealing for witnesses to come forward.

They described the suspects as in their early 20s. One was about 5ft 8in tall, wearing a green jumper and jeans with short dark brown hair. The other suspect was about 6ft tall, also with short brown hair.

The dog has a beige body, black muzzle, and has been microchipped. His temperament is described as placid and very friendly and he answers to the name Prince.

Neil Ewart, chairman of the charity Dog Theft Action, said canine theft was on the increase and they are working hard to get the police and judiciary to take the crime more seriously.

He said: "People are pinching dogs for all sorts of reasons, for fighting or breeding, or just to blackmail the owner into paying a ransom. It is quite an easy crime to commit and thieves can make a lot of money out of it, so we advise owners to treat their dog like a valuable object."

Anyone with information on Prince's theft can call Barnet police on 020 8200 1212.