Electricians on the Jubilee Line Extension and contractor Drake & Scull were in last-ditch talks on Wednesday to agree a termination payment linked to productivity increases.

Electricians are insisting that productivity can be increased only by a resumption of overtime throughout the project, but Drake & Scull says project targets could be met by reinstating overtime only on certain key sites. The contractor is willing to offer a golden handshake in excess of £1000, provided the electricians agree to its terms.

Sources close to the project said: "At the moment, the single biggest stumbling block is overtime. There is no meeting of minds yet." An electrician said: "It will create problems if some people are getting overtime and others are not. It would cause a lot of discontent." The source said: "If there isn't an agreement, there could be further problems here. Productivity needs to be increased and these talks offer the only chance of achieving that harmoniously." There is speculation that Drake & Scull could be forced to cut current bonus payments if the two sides fail to reach an agreement. The JLE electricians would fight this move.

The source added: "It's difficult to see what else they can do. The project needs something to give it a kick-start."