The rail operator First North Western has called on a union to put its latest pay offer to a ballot or agree to arbitration.

The company - which runs commuter services across the North West - and the union Aslef are involved in a long-running dispute over pay.

Train drivers have staged a number of strikes over the summer and talks have so far failed to find a solution.

Aslef is expected to consider the latest pay offer at a meeting next week.

Commuters have been hit by a series of strikes by drivers

Vernon Barker, managing director of FNW, said it had made an "excellent offer" to drivers.

He added: "Aslef has not submitted our offer to a vote by its members, our drivers, and continues to disrupt train services through strike action at the weekend and forced cancellations during the week."

But Aslef's Colin Smith said the latest pay offer was still "unacceptable".

He added: "The main contentious issues are still there.

"We want parity with the rest of the rail industry on pay and the conditions of the proposed six-month notice to leave employment are still unacceptable."

He said previous arbitration attempts had failed to result in meaningful negotiations.