Resistance from police, fire and transport authorities has frustrated attempts by Boris Johnson to save �300 million a year through sharing more services, London Assembly members heard today.

He wants organisations under the GLA such as the Met Police, Fire Brigade, Ambulance Service and TfL to save �900m by 2014 through sharing ‘back office’ services like IT.

But to date, only �1,200,000 a year has been achieved, the Assembly’s Budget committee was told.

It has led to a warning that the emergency services could face cuts if those targets weren’t met.

The warning shot was fired by the Mayor’s Chief of Staff, Sir Edward Lister, who told the committee that GLA organisations could see their budgets reduced if they put up “too much opposition” to sharing services.

Assembly budget chairman John Biggs said: “The challenge of getting everyone on board is making slow progress.

“So we’ll will monitor it closely to see if this programme actually starts to make real savings.”

His Budget committee had previously questioned whether the targets for such savings were realistic and warned they would be difficult to achieve.