Home Secretary Theresa May says she was unaware of a serous shortage of ponchos for the London Olympics.
The shortage means that over three thousand military capes will be redeployed to the Games from Afghanistan and Manchester.
John Lewis and Debenhams said they were unable to meet the demand 'especially of the more chic designs'.
Army leaders are said to be furious at the move. 'There will be some very wet soldiers in Helmand and Salford,' said one retired general.
Security analyst Tom Dyson said ponchos were a vital component of Olympic security.
'Without an adequate supply,' he said, 'people are vulnerable to attack by water suicide bombers and water pistol snipers.'
Fears are now growing that a shortage of umbrellas for the Olympics may encourage air borne showers.
'The Olympics will now be on amber alert,' Dyson said. 'The poncho shortage will put a real damper on the Games.'
Mr Dyson described Theresa May as 'a shower '.