Director Peter Rogers said he wanted to ensure that Kosovar and central European workers were treated properly and paid decent rates.
Rogers said: "We will ensure that our specialist contractors are employing these people properly.
I have spoken to all the labour agencies that we use, and if we find them exploiting these people it will be the last job they get with us.
"A handful of dodgy characters is shaming the industry and you have done a duty exposing this." Rogers added: "We will do some digging. We are paying a full rate when these people are supplied to site, so someone is ripping us off. I've asked our people to keep their eyes and ears open when they walk about site and report back to me." Construction minister Nick Raynsford declined to comment, but a spokesman for the DETR said the issue was a matter for the Department for Education and Employment.
A handful of dodgy characters is shaming the industry
Shadow construction and housing minister Nigel Waterson said: "I hope the home secretary gets a copy of the article in his red box this week because this is very disturbing. The safety aspect is of the most concern." A spokesman for the Health and Safety Executive said it did not believe that the use of illegal central European workers was a problem in construction and that it had no plans to investigate.
However, a spokesman for Bovis said: "Your article underlines the increasing problem of East Europeans who cannot speak English getting on to sites in London." Bovis recently expelled 18 central European workers from a Tesco development in west London because of concerns about their language ability and National Insurance credentials.
The action followed an accident in which a non-English-speaking central European was almost killed when a cherry-picker reversed over him. The HSE failed to interview the worker, who has since disappeared.
The Bovis spokesman said: "In the light of what happened at Tesco, Warwick Road, we have implemented fairly stringent safety checks on all our sites. We want to ensure it doesn't happen again. We can't police the entire industry but we can police our sites." Bob Blackman, construction secretary of the Transport and General Workers Union, welcomed Rogers' and Bovis' comments but criticised the HSE.