An employers’ group has written to the Unite union warning it not to encourage further wildcat strikes on construction sites

The Engineering Construction Industry Association (ECIA) sent the letter several months after it warned it was monitoring the union’s actions following protests against the use of foreign workers on sites across the UK.

The latest letter said the ECIA had advised its members of their legal options should the protests continue. It is not clear what advice it has given its members, but it is illegal for unions to organise a strike without an official ballot.

The news comes as Unite and the GMB prepared for talks with the ECIA on Wednesday to discuss pay rates for 2010. Both unions are demanding greater job security for workers.

Phil Davies, the GMB’s national officer, who was due to attend the meeting, said he would insist on a minimum wage for all workers under the National Agreement for the Engineering Construction Industry, regardless of nationality.

As Building went to press, both unions said their members would demand official industrial action if they failed to reach agreement.

Unite said: “Unite repudiates any unofficial action it is aware of.”