Otherwise they might face law changes to force them to do so.
Economic Development Minister Philip Ozouf yesterday met representatives of 12 sub-contracting firms who say they are struggling to find work because major firms are importing workers on to building sites direct from foreign countries.
He heard that the foreign workers were undercutting the locals so severely that they could not compete, and that long-term local residents were struggling to survive as a result.
Senator Ozouf told the protesters that he took a dim view of the practice.
He was writing to all construction firms to remind them that they should be employing locally where possible.
He admitted that firms were not doing anything legally wrong – they are given a licence on a contract or contract basis for a number of staff but are not told that the workers must be local.