All Royal Mail deliveries and collections will be "shut down" across East Renfrewshire during four days of strike action, a union has warned.

The Communication Workers Union (CWU) says services will be disrupted as a result of the industrial action, set to take place on August 26 and 31, as well as September 8 and 9, in a dispute over pay.

Royal Mail says workers have been offered a 5.5% rise but the union says this amounts to a 2% pay increase, a further 1.5% in exchange for a change in terms and conditions and a £500 bonus.

Craig Anderson, Scottish regional secretary of the CWU, said negotiations with bosses have broken down.

"We're taking this action because we've been given no other option," he added.

"The negotiations started in February regarding a pay rise for the workers within Royal Mail and the negotiations have broken down.

"They've imposed a 2% pay award without agreement. They offered another 1.5% based on signing away terms and conditions and a further £500 as a bonus for having targets that they knew weren't achievable, so there was never a 5.5% pay offer put on the table."

Mr Anderson called for Royal Mail to consider the fact that its staff are facing a cost-of-living crisis.

He added: "A fair offer from our perspective would be for them they sit back round the table with us and actually look at where or what comes out at the moment with a cost-of-living crisis, where the company's been with the profits that they've made and actually start negotiating on a percentage pay raise that reflects that.

"The difficulty we have at the moment is we don't know where inflation will be tomorrow, never mind where it will be in six months' time.

"Our members don't want to go on strike but we've been given no other choice."

Royal Mail chiefs say the CWU has "failed to engage" in discussions about changes that are needed to modernise the company, such as Sunday working as standard and flexible hours over the summer and Christmas period.

A spokesman added: "Industrial action is a significant act of self-harm.

"Unlike some other sectors like rail, our customers have many choices. Even since our last strike in 2009, the market has changed markedly. Our retail customers can switch their volume to our competitors at the press of a button and they will press that button if they need to.

"We have a 97% permanent workforce. We pay up to 40% more than our competitors and our people work for us for, on average, 17 years, reflecting the fact that working for Royal Mail is about more than just finding a short-term job to pay the bills.

"People stay and build careers with us.

"Our industry is very competitive and our customers are price sensitive. We have to deliver high quality at a lower cost. We can't charge our customers 40% more, so it is up to us to demonstrate the value and quality they get with Royal Mail.

"We also need to find better and more efficient ways of working so we can compete on price and protect jobs long term."