Royal Mail will consult on up to 10,000 redundancies after blaming striking workers for losses of £219m.
It said the move is in response to the “impact of industrial action, delays in delivering agreed productivity improvements and lower parcel volumes”.
The Communication Workers Union said the announcement was a result of “gross mismanagement” aiming to turn Royal Mail into a gig economy style parcel courier.
Royal Mail said it had started the process of consulting over “rightsizing the business in response to the impact of industrial action, delays in delivering agreed productivity improvements and lower parcel volumes”.
The company is seeking short-term cost efficiencies through the planned reduction of 5,000 full time equivalent roles by March and around 10,000 by August.
It said this was expected to require up to 6,000 redundancies by August.
It came amid a warning by parent group International Distributions Services that Royal Mail is expected to tumble to a £350m operating loss for the year after being hit by industrial action.
The cuts announcement comes a day after Royal Mail workers in the Communication Workers Union (CWU) launched a fresh strike in a long-running dispute over pay and conditions.
“The announcement is the result of gross mismanagement and a failed business agenda of ending daily deliveries, a wholesale levelling-down of the terms, pay and conditions of postal workers, and turning Royal Mail into a gig economy style parcel courier,” said CWU general secretary Dave Ward.
“What the company should be doing is abandoning its asset-stripping strategy and building the future based on utilising the competitive edge it already has in its deliveries to 32 million addresses across the country.”
The CWU said it is calling for an urgent meeting with the company’s board.
Royal Mail chief executive Simon Thompson said: “This is a very sad day. I regret that we are announcing these job losses.
“We will do all we can to avoid compulsory redundancies and support everyone affected.
“We have announced today losses of £219m in the first half of the year. Each strike day weakens our financial situation.
“The Communication Workers Union’s (CWU) decision to choose damaging strike action over resolution regrettably increases the risk of further headcount reductions.”
On Thursday, around hundreds of thousands of Royal Mail workers, who are members of the CWU, walked out in a dispute over the postal service’s senior management proposals for structural change.
The dispute, which began in spring 2022, escalated over previous weeks after the union said they were “threatened” management would withdraw on all legally binding national agreements, “unilaterally impose changes and side line union representatives”.
Following this, the union announced 19 further days of strike action in the build up to Christmas, with severe delays and disruption expected.