As hundreds of First Bus drivers were joined on strike by their Bolton and Bury colleagues in the second 24-hour shut-down in four days, 350 postal workers were also due to walk out.

The 350 mail staff, mostly based at the sorting office in Hallgate, were today striking for the third time, having previously staged single days of industrial action on August 21 and 24.

They are in dispute with the Royal Mail over nine local redundancies which bosses of the Communications Workers Union say were made without their consent.

They claim this was a blatant breach of a deal with bosses that such decisions be reached through negotiated agreement.

The CWU is seeking reassurances from employers that they won't take further decisions without agreement but so far no promise has been made.

The Chamber of Commerce has already voiced concern about the damaging effects the strikes are having on an already recession-hit economy.

But representatives of both unions say they cannot rule out further action.

It is believed the sorting offices have only just cleared the backlog that built up because of the previous strike.

CWU area representative Paul Fenny said: "We are not asking for the world here. All we want is a reassurance from Royal Mail that they won't be breaching the agreement again.

"But they don't seem prepared to do that so, regrettably, we are on strike again. After each day's action we have a union meeting to decide what further action, if any, to take."

The strike is due to run until 5am tomorrow. Mr Fenny said the original strike plan had been to take just one hour off but when Royal Mail dusted down a piece of industrial relations legislation from the Victorian era that meant they would lose a whole day's pay for that hour's action, they decided to walk out for the full 24 hours.

A Royal Mail spokesman said it had contingency plans in place to reduce disruption including the use of managers to minimise the impact of the strike.

First Bus staff are staging a series of one-day strikes – the first of which took place on Friday – because they have not been offered a pay rise this year.

First Group, the parent company of First Bus, recently announced record profits of £134m.

Further days of action are planned for the remaining Mondays of the month.