Members of the GMB Union have voted to strike on two of the busiest days of the year.

The dispute centres on drivers and conductors having to work beyond 8pm on Christmas Eve and New Year's Eve.

But the union says it wants to maintain a dialogue with operators NET and hopes it can avoid the first action scheduled in just four days' time.

On Friday, members of the GMB voted in favour of industrial action - saying it was only fair to wind down services in line with other public transport operators.

NET has so far refused to comment on the dispute, saying talks are at a sensitive stage.

A deal which offered improved pay for the extra hours has already been rejected by the workers.