A Royal Mail boss said today that a 30,000-strong recruitment blitz was not designed to "break" a union as last-ditch talks aimed at preventing this week's crippling strikes went ahead.
Operations director Paul Tolhurst said the temporary workers - around twice the normal amount taken on this time of year - were needed to "keep the mail moving" and avoid a big backlog building up.
He told GMTV that "he hoped there was hope" that the strikes on Thursday and Friday could be avoided, but said the company was gearing up for industrial action.
Royal Mail bosses are to meet the Communication Workers Union (CWU) at an undisclosed location later in a bid to break the deadlock.
Relations between the two sides became increasingly fractious over the weekend when the company announced the hiring plans. Union leaders responded by considering a legal challenge to the move.
Mr Tolhurst told GMTV: "We are not trying to break the union.
"We recognise the CWU has a vital role to play. But the most important thing for us is to keep the mail moving.
"The (strikes') purpose is to damage customer service."
Of the chances of a breakthrough at the crunch talks, he said: "I hope there's hope.
"We are still talking, but it is a very complicated set of negotiations.
"We are talking and trying to find a way forward."
One of the Royal Mail's biggest competitors is looking to capitalise on the walkouts.
TNT, the country's largest private mail company, wants powers to put its own postmen on the streets and offer a door-to-door service, something it cannot do at the moment.
Mr Tolhurst said: "Yes we are very concerned.
"Letter volumes that are staying are being delivered by our competitors and we are very worried about that."
Nick Wells, chief executive of TNT Mail UK, revealed his company was prepared to take on an expanded door-to-door delivery service, but admitted it would be "a massive challenge".
TNT relies on the Royal Mail for the final mile of its postal network, but has completed several trial runs in Liverpool, Manchester and Glasgow which have seen postmen in orange uniforms make door-to-door deliveries.
Mr Wells told the Guardian: "If anyone can do it (a rival service) TNT can.
"There are going to be operational challenges, we would be ridiculously naive to think otherwise. It's a massive challenge on a huge scale but the reality is we have the customers, appetite and resources."
A Royal Mail spokesman said yesterday that there had been around 80 meetings with the CWU in recent months.
"In addition (chief executive) Adam Crozier has invited (CWU general secretary) Billy Hayes to meet him more than a dozen times and Billy Hayes has not even responded," the spokesman said.
CWU officials said they believed the recruitment of temporary staff during a strike was illegal and they received backing from other union leaders.
Mr Hayes said: "I think it is a stupid move. It will inflame things."
A union official added: "We will be looking at the legal side of this and we are calling on recruitment agencies to be aware of the law if they are asked to supply temporary workers to the Royal Mail."
Regulations amended in 2007 state that an employment business may not supply a temporary worker to a hirer to replace an individual taking part in an official strike or any other official industrial dispute.
Paul Kenny, general secretary of the GMB union, said: "It is beyond belief that in the very week Lord Mandelson has delayed employment rights for agency workers, his department has given the go-ahead for Royal Mail to hire 30,000 agency staff to break a lawful trade dispute.
"There are strict laws that forbid employers and employment agencies using agency staff to break a lawful dispute and it is the job of Lord Mandelson's department to enforce those laws."
Mr Tolhurst also played down the prospect of any violence on picket lines if strikes went ahead.
There are reports of police gearing up for possible trouble when postal workers picket outside sorting offices and branches.
Mr Tolhurst said: "Clearly I would be very concerned if there was any violence on picket lines.
"We have had some regional disputes and the picket lines have been extremely well-behaved. Postmen have been conducting themselves well and so have the managers.
"I would hope we don't have any trouble like that."