Three hundred Amec workers at Heathrow Terminal 5 have added their voices to the demand for extra bonuses.

The workers, who are responsible for concrete paving across the project, are the latest to demand an extra £1 an hour to match bonuses won by electricians and steelworkers.

The disclosure follows news last week that main contractor Laing O’Rourke had taken the first steps to challenge the legality of a ballot of civil engineering workers, also over bonuses, in an attempt to avert further industrial action.

The Amec workers are represented by UCATT, T&G and GMB. A union source confirmed that they had lodged a claim for the extra money.

The source said: “This has been dictated by the discussions Laing O’Rourke and BAA have held with other parties on the site. Once one sector was awarded the bonus, it gave the others a reason to ask for the same.”