Police hunting for missing 12-year-old Tia Sharp have found a body at her grandmother's house.

Scotland Yard said a murder inquiry had been launched after the discovery "following a search of the property this afternoon".

Police also said they were searching for Tia's grandmother's partner Stuart Hazell and warned the public not to approach him.

The grim announcement came just hours after police began a forensic search of Tia's grandmother Christine Sharp's terraced house. Mrs Sharp, who was led from her home with police shortly before the search began, told reporters her boyfriend was out helping in the search. A cordon was later placed around the house on The Lindens, New Addington, near Croydon, south London, and white-suited forensics officers were seen going inside.

Hazell, who was interviewed by police as a witness on Wednesday but then released, claimed Tia had set off for the Whitgift Centre in Croydon last Friday to buy flip-flops having spent Thursday night alone with him while her grandmother was at work. He later claimed another witness saw Tia leaving the house shortly after midday although police said that sighting had not been confirmed.

Hazell reportedly has a criminal record including offences of theft, handling stolen goods and dealing drugs. Asked about his past, he told reporters: "Everyone's got a shady past. My previous has nothing to do with it." He dismissed claims his father had contradicted his version of events. His father, Keith, earlier claimed his son had walked her to the tram stop. Mr Hazell said: "My dad likes a drink, he's got good intentions but he said everything back to front. If I'd have walked her to the tram stop I would have come with her to Croydon then none of this would have happened."

Police have not revealed where the body was discovered. Officers were seen taking a ladder into the property this afternoon, sparking rumours that the body may have been found in the loft.

Later, Commander Neil Basu, the area commander responsible for south east London, said: "Clearly there will be many questions about the investigation into Tia's disappearance and I want to take this opportunity to clarify some of the speculation. When police investigate cases as difficult and challenging as this, it is important that we do not just focus on one line of inquiry. For example we had over 60 reported sightings of Tia, 800 hours of CCTV footage to examine and 300 plus calls into the incident room. All of these lines of inquiry were in the process of being followed up.

"A number of searches took place at the address. When Tia was first reported missing, officers searched her bedroom as is normal practice in a missing persons inquiry. A further search of the house took place in the early hours of Sunday morning by a specialist team. This was then followed by another search of the house by specialist dogs on Wednesday lunchtime. What we now need to establish is how long the body had been in the place where it was found. This will be subject of the ongoing investigation and it would be wrong to jump to any conclusions until all the facts have been established. Throughout the inquiry, we have liaised closely with Tia's family. We have kept them updated and have provided support at all times. Today's pre-planned search was undertaken with their full co-operation.

"Our priority now is to establish the facts of the case and to assist us with this, we are keen to speak to all those people who last saw Tia. In particular, we want to trace Stuart Hazell as a matter of urgency. We have issued a picture of Mr Hazell and would urge anyone who may know his whereabouts to contact police via 999 and not to approach him. We would like to thank the public for all of their help and continued assistance at this difficult time and we will keep you updated."