A tube worker has been fired and two colleagues disciplined after punches were thrown during a confrontation with an alleged fare dodger.

London Underground said action was taken against its employees after CCTV footage was examined.

But the RMT union claimed the sacked worker was the victim of an 'appalling miscarriage of justice' after intervening to stop a serious assault on colleagues.

A pregnant tube worker was said to have been punched in the stomach during the violence at London Bridge Underground station in November.

A staff member who challenged the fare dodger to produce a ticket or oyster card was accused of 'inciting or provoking an incident', according to the RMT.

The row over the disciplinary action could lead to a strike after union officials ordered a ballot of their members at London Bridge.

The RMT today demanded the sacked worker be reinstated and disciplinary procedures against two others be dropped.

This is one of the most appalling abuses of the LU disciplinary procedure that the RMT has ever come across. This was a shocking, violent incident and those that bore the brunt of it should have been supported and commended by the company. Instead they have been sacked or disciplined in what is the most appalling miscarriage of justice. MICK CASH, GENERAL SECRETARY, RMT

London Underground called on the RMT to discuss the cases directly with managers.