Workers are demanding compensation for travelling time

Amicus wants all staff paid �25 per day to compensate for the 90 minutes it can take to reach the construction site due to security and transport arrangements.

Employers offered an additional �7 but Amicus said 97% of its 500 members who work for 14 construction companies at the west London site, voted against it.

Amicus says it will now ballot its members on whether to strike.

BAA hopes the terminal will be in operation by 2008.

Civil engineer workers at the terminal get paid �25 per day for travelling time.

Amicus, which represents electrical and mechanical engineers and steel erectors at T5, says it wants parity of pay for its members.