Royal Opera House M&E contractor Balfour Kilpatrick has drafted in extra electricians in a bid to keep the project on schedule after the ban on overtime by sparks.

Sources at the opera house said 40 new electricians reported for work this week and more were scheduled to come from other Balfour Kilpatrick projects. An opera house insider said: "They know they're up against it time-wise, but there are almost 1000 workers here at the moment and there isn't enough room to take any more. They'll be falling over each other."

The insider added: "No one on site believes the opera house will finish on time any more."

Last week, opera house electricians claimed that Balfour Kilpatrick project director John Moore told them it did not matter if the opera house missed its December deadline. Balfour Kilpatrick refused to comment. The firm was scheduled to meet the AEEU union on Wednesday to try to end the dispute.

An electrician said: "We want an hourly rate of £13 and a termination payment. If they want this job finished, they have got to start looking after the men building it." Construction manager Schal was unavailable for comment.