Despite ongoing wrangles with Westminster about how the crossing will be paid for, the Scottish Government insisted it was "on time and on budget" to open by 2016 and would be funded by "existing capital resources" if necessary.

The parliamentary process was kicked off yesterday when Finance Secretary John Swinney reached a deadlock with the Treasury over his proposals to bring forward funding from future years to pay for the bridge, the cost of which is estimated at between £1.7bn and £2.3bn.

A counter-proposal by the Treasury to pay £1bn towards the cost was rejected as a "red herring" as it was claimed this would come from money already allocated to Scotland under the Barnett formula.

Transport Minister Stewart Stevenson said: "Introduction of the Forth Crossing Bill marks a historic day for Scotland and makes this Government’s commitment to delivering the Forth replacement crossing in 2016, on time and on budget, abundantly clear.

"Given the real uncertainty of the future viability of the current Forth Road Bridge, Scotland simply cannot afford any delay to the Forth Replacement Crossing.

"We are taking the earliest possible action to prevent serious disruption to cross-Forth traffic arising from maintenance and repair works on the Forth Road Bridge."

The cable-stay crossing, which comprises a two-lane carriageway with hard shoulders, spanning approximately 1.7 miles in length, has been fiercely resisted by environmentalists, who say it will lead to increased traffic levels, but is viewed as essential by Scotland’s main political parties and business organisations.

The current bridge is showing signs of deterioration and is not seen as suitable as the long-term main crossing of the Firth of Forth, although work is under way in an effort to halt corrosion on its main cables. Edinburgh Council is also opposed to progressing with the plans until 2011, when more will be known about the corrosion in the cables of the existing Forth Road Bridge.

Labour finance spokesman Andy Kerr said there were still questions over the funding of the bridge. He said: "The SNP are failing the credibility test over the new Forth Bridge by producing a Bill that fails to say how the new crossing will be paid for. They have even seen fit to reject a £1bn offer from the UK Government."

Tory shadow Scottish secretary David Mundell said an incoming Conservative government at Westminster would "sit down and hold talks" with the Scottish Government to discuss possible funding ideas.

He said: "We would strive to find solutions, and avoid the megaphone diplomacy and the grudge and gripe which has characterised inter-government relations for far too long."

Liberal Democrat transport spokeswoman Alison McInnes added: "The Scottish Government need to sit down with the Treasury and establish a better funding package for this vital bridge.

"The proposed funding mechanism is quite simply unacceptable."

Green Party co-leader

Patrick Harvie said the Bill was "unaffordable".

He added: "Even assuming the price wouldn’t spiral out of control during construction, it’s already the most expensive bridge of its type ever proposed.

"Generations of Scots would pick up the bill for the biggest bung to the road-building lobby this country has ever seen."

A recent poll found that just over one-third of people support the plans for a new Forth Road Bridge. More than half of Scots say that the current bridge should be repaired instead.