A UNION has accused rail bosses of running a campaign of “lies and dirty tricks”.

The RMT has started balloting staff at Northern Rail on strike action in an increasingly bitter dispute about the use of agency staff.

The union claims that over the Bank Holiday weekend Northern Rail management attempted to interfere with the ballot by giving misleading information.

RMT general secretary Bob Crow said: “It is disgraceful that Northern management, instead to sitting down with the union to address the issues at the heart of this dispute, have resorted to a campaign of smears, lies and personal attacks in a desperate attempt to influence the outcome of this secret trade union ballot.

“There is rock-sold evidence of a deliberate and cynical drive to use casual, agency staff to undermine job security, pay and working conditions on Northern Rail and our members are furious that not only have the company refused to stop this practice but they are driving it forwards.”

Northern Rail last night declined to respond to the claims.

Last week, Northern Rail human resources director Adrian Thompson, said claims by the RMT that the company was gradually replacing employees with agency staff was “completely unfounded and untrue”.