A union representing postal workers at Britain's Royal Mail said on Wednesday its members would take fresh strike action at the end of the month in a dispute over terms and conditions.

Some 115,000 postal workers are already due to take industrial action on Thursday and Friday following a similar walkout last month, in one of Britain's biggest strikes this summer.

"We have today called a further two days (of strike action) on 30th September and 1st October over attacks on terms and conditions," the Communication Workers Union (CWU) said on Twitter.

Royal Mail, which has said its business is losing 1 million pounds ($1.2 million) a day, said on Wednesday strike action had weakened its financial position. The CWU had turned down a request to call off this week's strikes, it added.

"The CWU’s approach is setting us on a perilous path," it said in a statement.

"We remain ready to talk with the CWU to try and avert damaging industrial action ... But any talks must be about both change and pay. Change is the route to higher pay."

A range of sectors, from the railways to the courts, have been hit by strikes in recent months as wages fall further behind soaring inflation that topped 10% in July.

Royal Mail said it was working to minimise delays and disruptions to customers during the strikes.

(Writing by Sachin Ravikumar, Editing by Kylie MacLellan)