Workers at Belfast aerospace company Bombardier Shorts are threatening a work to rule protest at the weekend in opposition to cutbacks in overtime, according to the firm.

Bombardier has been informed staff will refuse to work late shifts from Saturday, according to a spokesman. Neither of the trade unions representing most of the 5,500 workforce - Amicus and the Transport & General Workers' Union - were available for comment. The industrial action comes after talks at the North's Labour Relations Agency broke up this week.

The talks broke up after internal representatives of the two unions - instead of the body which represents all unions at the factory - went to the discussions .

A Bombardier spokesman said the unions had set down "pre-conditions" before they would enter into negotiations on the pay contract renewal.

For their part, the two unions said that as two out of three unions had voted for industrial action, it was more appropriate if their shop stewards were the only union representatives to take part in the talks.

They insisted issues surrounding the threatened industrial action should be addressed first to pave the way for talks on wider issues.