Protesters are set to target an emergency mail sorting centre in Dartford, which they say is ruthlessly exploiting workers to counter postal strikes.

Angry trade unionists, activists and sympathisers are due to meet at Royal Mail’s giant warehouse, in Sandpit Road tomorrow, in a bid to see the “scab” facility closed down.

Royal Mail says temporary staff at the 160,000 sq ft warehouse are being used to clear mail backlogs caused by industrial action in London and the South East.

But supporters of campaign group Right to Work, which organised the rally, argue otherwise. They say the 200 agency staff employed there are being used as strike-breakers to fill the gap left by postal worker walk-outs.

About 300 staff at Royal Mail’s sorting centre, in West Hill, are set to man picket lines on Thursday in a continuing dispute over pay, conditions and modernisation plans.

It will be the second walk-out to hit postal services in the borough since the Communication Workers Union (CWU) began national strikes on Thursday, October 22.

Charlie Kimber, from Right to Work, which is supporting CWU workers, said: “You can’t employ people to do the work of striking workers. It’s being done to undermine the strike.

“We recognise the people doing it must be seriously desperate and we do not see them as the enemy. It’s more the policy we are against. We would like to see the facility closed and for there to be a settlement to the dispute.”

Mr Kimber said he expected about 40 protesters to meet at the warehouse for the start of tomorrow's 6am shift, when they hoped to encourage workers to join the CWU’s fight.

“We don’t expect them all to stop on the day but it would be great if some of them do join the striking postal workers,” he said. “They will all be tossed aside as soon as they’ve played their role in undermining the strike. They will just be shown the door.”