Ken would cross London Underground's barricade

Speaking in the first Mayoral question time since his re-election Mr Livingstone said: "this position I find completely and utterly unacceptable. I have a long history of defending trade unionism... Londoners should not be put to this inconvenience and disruption.''

This is the strongest condemnation yet by Labour's Mayor of the proposed strike action which is due to start on Tuesday evening and continue through Wednesday.

The RMT Leader Bob Crow - until recently a board member of Transport for London - described Mr Livingstone's comments as "not helpful".

Mr Crow has supported strike action over the closure of Network Rail's pension scheme to new employees.

Right to strike

But a visibly emotional Mr Livingstone told London Assembly members trade unionists should not abuse the right to strike.

He admitted the closure of basic pension schemes was, "one of the greatest obscenities in public life", but stressed that there was no need for strike action.

''I doubt if there is anywhere in the public sector and most probably not in the private sector, where pay and conditions on offer are as generous as this currently under discussion.... Londoners should not be punished because of a national squabble between Network Rail and the RMT,'' he continued.

The Mayor has faced repeated calls from the assembly to sack Mr Crow from the board of Transport for London, a move he has rejected as "gesture politics".

Assembly Members were told in blunt terms that there is an ''absolute determination'' to strike on Tuesday.

On his efforts to resolve the dispute, Mr Livingstone said : ''I have to tell you, I have not the slightest hope whatsoever that we will be successful."