The delays are inexcusable

CBI's Digby Jones

The Confederation of British Industry (CBI) also expressed concern that many top priority schemes had still not got off the ground.

"Frankly the delays are inexcusable and something the travelling public does not deserve," said CBI director general Digby Jones.

The CBI's criticism of the plan follows last month's attack from the House of Commons Transport Committee.

No shirking please

Mr Jones said that £12bn out of the missing £15bn was needed to help the UK's ailing rail network.

And he called on Transport Secretary Alistair Darling "not to shirk a series of key decisions during the next make-or-break 12 months".

"Major projects not given the go-ahead within the next 18 months are unlikely to be built by 2010," Mr Jones warned.

The CBI praised the government's overall commitment to long-term investment, but called for more details on how the money would be spent and for faster delivery on decisions.

The government's transport plan sets aside £180bn over the next 10 years to pump fresh funds into the UK's air, rail and road infrastructure.