David Walliams' Thames charity swim appeared to be in jeopardy after the comic developed a serious stomach bug.

Walliams has been struck down by the bug after completing only 38 miles of the gruelling 140 mile swim to raise money for Sport Relief.

This morning the Sport Relief Twitter feed said: "David has woken up with an upset stomach – Thames Tummy."

"Poorly David gets encased in his wet suit. Didn't sleep well at all.

"Despite the bug he's picked up though David is back in the water aiming for another 18 miles today."

However the Little Britain star soldiered on and hopes to finish up at Goring.

The Thames’ murky water which is believed to contain bacteria such as E.coli, salmonella and hepatitis is possibly behind Walliams’ upset stomach.

Walliams is attempting to swim the length of the River Thames from Lechlade Gloucestershire to London over eight days.

The comic who is married to supermodel Lara Stone has also received treatment from physiotherapists for aches and pains.

This isn’t the first time Walliams has swam for charity. In 2006 Walliams swam the Channel, raising £1 million in aid of Sport Relief.

David Walliams begins Thames charity swim