Northern Rock is to be nationalised as a temporary measure, Chancellor Alistair Darling has said.

Neither of the two private proposals to take over the beleaguered bank offered "sufficient value for money to the taxpayer", Mr Darling said.

He said the public would gain if the government held on to Northern Rock until market conditions improved.

Ron Sandler, nominated by the government to run Northern Rock, said savers' deposits would be secure.