A co-ordinated strike would cripple Tube services

The rail union Aslef said there had been a "serious breakdown in industrial relations and trust" with management.

Aslef said that any walkouts would be co-ordinated with the RMT union which has already staged two strikes in a row over new rotas and safety.

LU said it was consulting unions on new employment procedures and was committed to a culture of fairness and trust.

Aslef accuses LU of ignoring agreements, imposing change without negotiation and inflicting "draconian" punishments.

We cannot allow this position to continue Aslef's national organiser Andy Reed

The union's national organiser Andy Reed said industrial relations varied from hostility to anarchy.

He said: "[Mayor of London] Ken Livingstone wrote to the union in November 2002 promising a review of London Underground Limited's harassment procedure. In over two years, LUL has failed to progress this.

"Discipline appeals appear to be pointless exercises rather than serious re-considerations.

"Representatives are not allowed time off for union duties. Transfer agreements are regularly ignored. We cannot allow this position to continue."

The strike by the RMT closed 40 stations

He said the union would be recommending a series of 24 hour strikes when the ballot papers go out next week to its 2,200 Tube train drivers. The result will be declared on 13 February.

An LU spokesman said: "London Underground is in the process of updating its employment procedures. We have submitted some procedures to our trade unions for consultation and comment.

"We are committed to working with Aslef and all our trade unions to resolve the kind of issues they are raising through consultation and negotiation."

Talks to resolve the dispute with the RMT resumed on Thursday.

The dispute centres on new rotas, due to come in on 5 February, which the RMT says will displace hundreds of station staff and leave some stations understaffed and unsafe - something denied by Tube bosses.

It has already prompted two strikes, on New Year's Eve and last Monday. LU described the impact as "minimal".

But the union said the situation was "chaotic" and claimed staff were working in positions for which they were not fully trained.

It has threatened to ballot its members for additional industrial action short of a strike over claims safety was compromised during the first strike although this is denied by LU.