Wembley contractor Multiplex has agreed a package of special incentive payments in an attempt to complete the project in time for the FA Cup Final in May

The incentives agreed between Multiplex, Amicus and the GMB are believed to be worth about £1m.

The deal, which centres on the completion the roof, could become a benchmark for other projects.

The agreement comes two weeks after Multiplex admitted that it faced a £45m loss on the troubled scheme.

Multiplex has drawn up a 21-stage timetable with unions aimed at completing the roof by mid-October. It is understood that Multiplex has agreed a set payment to steelworkers for each stage completed on time, with the maximum amount on offer in the region of £1m.

Ashley Muldoon, project director on the stadium, said the deal ought to make it possible for the project to be finished in time to stage the final.

He said: “This commitment from the steelworkers at Wembley, combined with Multiplex and the trade unions, reaffirms our common goal that completion will be achieved in time.”

Frank Westerman, Amicus’ regional organiser, said both management and workers were committed to finishing the scheme in time for the final. He added that although there was no provision for this arrangement under the standard National Agreement for Construction and Engineering Industries that had been negotiated between unions and the Employers Federation, other contractors and clients might take a lead from it, particularly on high-profile projects.

It is understood that shop stewards can now decide how and when payments will be made to workers. Payments may be added together to create a tax-efficient “finishing bonus” at the end of the scheme.

A spokesperson for Multiplex this week insisted that the incentive payments would not cause further financial loss.

He said: “We always intended to introduce some form of incentive as the project neared completion. These costs are already built into our budget and will not affect the current financial situation.”