Fears were growing last night for a businessman and his family who have been missing since their country home was burnt to the ground in a suspected arson attack.

Christopher Foster, 50, his wife Jillian, 49, and their daughter Kirsty, 15, were last seen a few hours before their £1.2m property at Oswestry, Shropshire, was destroyed on Tuesday. The family are believed to have gone to a party on Monday evening and returned just before the blaze started.

Mrs Foster's brother, Roger Doley, said he had been visited by police searching for his sister and her family. "I was gripped with dread. I couldn't believe what [the police officer] was telling me," he added. They won't be able to go into the house for days. The waiting is killing me."

Police placed a mile-wide cordon around Osbaston House yesterday but were unable to enter the building because it was deemed unsafe by firefighters.

Detectives did, however, find the charred corpses of three horses and a burnt-out fleet of sports cars in an outbuilding and stables which were also gutted. Two dogs which usually live in kennels in the grounds are missing. However, they could be inside the house.

Emergency crews arriving to fight the blaze were obstructed by a horsebox which had been deliberately placed behind the electronic gates at the end of the drive to stop them being opened.

The mystery surrounding the family deepened yesterday when it emerged that the insulation business from which Mr Foster earned his millions had recently gone into liquidation. Two years ago, he alleged that two men tried to blackmail him for £100,000, demanding the money after a land deal in Cyprus fell through. The defendants were subsequently cleared at their trial.

Today, police will study closed-circuit security tapes recovered from a camera in one of the outbuildings. Eighty officers are involved in the inquiry but their progress is likely to be slow until the house is deemed safe to enter, which could take days.

Detective Superintendent Jon Groves, of the major incident unit at West Mercia Constabulary, said last night: "There was a CCTV system at the property, which has been recovered and will be examined over the coming days.

"The house, a garage and stable block and another outbuilding were severely damaged. Two horses in the stable and another in the outbuilding have been found dead. Two dogs, which we believe were in a kennel block, are missing. As soon as the house is deemed to be safe, a search will be carried out to establish if anybody was inside. Forensic investigators have been at the scene and house-to-house inquiries carried out."

Mr Foster was previously the managing director of Ulva Limited, a company which provided insulation for oil rigs and went into compulsory liquidation in September 2007. A company called Ulva Insulations Systems Limited is now based at the same premises in Telford, but a spokeswoman there said yesterday that Mr Foster had nothing to do with the new concern.

According to a friend, Mr Foster had recently voiced financial worries. Gordon Richards, a builder, said: "When I saw Chris a few days ago, he seemed happy but he said he was feeling the pinch at work because of the credit crunch."

Nevertheless, neighbours said the family continued to enjoy a luxurious lifestyle. They holidayed in Dubai and Mr Foster owned two Porsches and an Aston Martin. His hobbies include shooting and fishing.

Mrs Foster, who used to work as Ulva Limited's secretary, drove a 4x4 car with personalised registration plates and enjoys horseriding with her daughter, according to friends. Kirsty Foster attends Ellesmere College, a co-educational boarding school in north Shropshire.