A Wiltshire couple whose son has been battling the deadly Sars virus for two weeks have spoken of their relief on receiving a telephone call to say he was on the mend.

John and Gill Marriott, of Christian Malford, said they hardly recognised their 33-year-old son Christopher's voice when he called from the isolation ward of a Hong Kong hospital, where he has been in quarantine for a fortnight.

The couple said they were overjoyed to hear from him and have spoken to him every day since he first called last Wednesday.

They have also remained in close contact with his wife Pippa and their three children who also live in Hong Kong.

His father Mr Marriott, 69, a former RAF Wing Commander said: "We watch the television and the number of deaths were increasing in Hong Kong but we hoped he would be okay. When he telephoned his voice was totally different, which was probably something to do with the treatment."

The Sars virus has swept across South-East Asia, killing more than 100 people in Hong Kong in the past two months.