A government deal with the medical insurer Bupa to use a private clinic for NHS operations came under attack from unions yesterday.

"The key fact here is capacity," said a government spokesman. "There is a shortfall of capacity in the NHS...and the key issue is what you can do practically to increase capacity in the NHS."

The Conservatives have cautiously welcomed the deal, which will mean 12,000 NHS operations will be performed at the clinic in Redhill, Surrey.

However, the GMB's John Edmonds described the announcement as "a slap in the face for the public service unions".