Sir Edward Heath has been admitted to hospital after developing a blood clot on his lung.

The 87-year-old former prime minister was transferred to a London hospital after being flown by air ambulance from Austria on Tuesday night.

He developed the pulmonary embolism after developing a stomach complaint.

"Following treatment in hospital in Salzburg for a minor stomach upset, a small clot on the lung was discovered," said Sir Edward's private secretary.

"Sir Edward Heath is now receiving further treatment for this condition at the King Edward VII hospital in London."

Iain Duncan Smith expressed his hope that Sir Edward would be discharged soon.

"I am sad to hear that Sir Edward Heath has been taken ill," he said.

"Naturally, we all wish him a very speedy recovery. The thoughts of the entire Conservative Party are with Sir Edward at this time."

A pulmonary embolism is commonly associated with deep vein thrombosis.