A minister has moved to allay Labour MPs' fears that the government might stage a back-door privatisation of Royal Mail, telling them it will not renege on a manifesto pledge to keep the postal operator in public hands.

Opposition to any change in ownership has grown. Nick Brown, a former cabinet minister and an ex-party whip, added his name to a Commons motion on the issue yesterday, taking the number of Labour signatories to 185, more than half the parliamentary party.