Council chiefs in Birmingham today said they might contest a employment tribunal ruling which, it is claimed, could cost the authority up to £600 million in back pay to women workers.

Nearly 5,000 female council workers employed in roles such as cooks, cleaners and care assistants have won a sex discrimination case going back a decade after claiming they were excluded from bonus payments which were paid to male staff on the same pay grade.

Union chiefs have said the landmark ruling will cost around £30m in compensation settlements, but solicitors today claimed the figure could be as high as £600m.

A 160-page judgement from the employment tribunal dismissed Birmingham City Council’s defence.

The tribunal had been told men in jobs such as refuse collecting, grave digging and road sweeping were paid bonuses, while women were not, meaning men could earn as much as four times as much as females on the same pay grade.

Jobs chief Councillor Alan Rudge today said that the city was considering an appeal against the tribunal ruling and lawyers were studying the 160-page judgement before making any decisions.