Australian contractor says that work would have to "run like a Swiss watch" for Wembley to be completed on time.

Contractor Multiplex today warned today that there was a substantial risk the new Wembley Stadium would not be finished in time for the FA cup final on 13th May.

Martin Tidd, Multiplex's UK managing director, said there was a 70% chance the stadium would be substantially completed by 31st March, the date the stadium has to be handed over to Wembley National Stadium Limited for testing prior to the cup final.

Tidd said, "The substantial risks still remaining are subcontractor performance, design changes, industrial relations, the weather and final the integration and commissioning of systems."

"Work would have to run like a Swiss watch if the stadium was going to completed according to schedule".

Multiplex said most risky job was getting the roof finished on time. Work to be completed includes taking down temporary works supporting the roof trusses spanning between the east and west stands, and finishing off the roof cladding.

The biggest threat to work on the roof is high winds. According to Tidd work on the roof has to stop if wind speeds exceed 7 knots. Work on the pitch and seating cannot be completed until the temporary works are out of the way.

Work would have to run like a Swiss watch if the stadium was going to completed according to schedule.

Multiplex managing director Martin Tidd

Tidd added Multiplex would soon be in a position to definitely say whether Wembly would be ready saying, "We think it is too early to call whether it will be here or at Cardiff. We will be able to assess this in three weeks time."

The contractor is also putting pressure on its subcontractors to get the job finished.

"We have over 3,500 workers out there, there's tremendous pressure on the trade contractors. We are doing as much as we can to manage the trade contractors performance," said Tidd. However he said this would not come at any price. "We will not be a hostage to ransom and we are looking to our guys and the unions to manage things fairly."

Multiplex revealed in December that it faces losses of up to £70m on the project.