Fears for thousands of retail jobs at the ailing chain Wilko deepened on Wednesday evening when trade union officials warned that the majority of its shops were likely to close within days.

Sky News has learnt that administrators at PricewaterhouseCoopers (PwC) are in advanced talks to carve up parts of the 400-strong chain, with Poundland’s owner, Pepco Group, in discussions to acquire roughly 100 stores.

B&M European Retail, the London-listed discount chain, is also in negotiations to take on between 40 and 50 shops, according to one insider.

Other value retailers, including TOFS, which is owned by the private equity firm Duke Street, have lodged offers to acquire smaller parcels comprising about ten sites.

Retail industry sources said an announcement was expected to be made by PwC on Thursday outlining the sale agreements with at least some of the bidders.

Even if agreements with Pepco, B&M and TOFS are finalised, it is likely to mean that more than 200 Wilko stores will face permanent closure.

That could mean that well over 6,000 jobs, including those of Wilko head office staff, would be lost, although the eventual figure could be substantially higher than that.

In a statement pre-empting an announcement from PwC, the GMB Union said: “In a meeting with administrators today GMB Union was informed there is no longer any prospect that the majority of the business will be saved.

“This means redundancies for staff in store and at call centres will begin during the coming week.

“Some stores may be bought, either individually or as part of larger packages, but significant job losses are now expected.”

The union said talks had been taking place about a larger deal for about half of Wilko’s stores with an unnamed bidder, and Sky News understands that there remains a faint, but receding, possibility that this could yet be salvaged.

Andy Prendergast, GMB national secretary, told Wilko’s 12,500-strong workforce that it would “continue to support members through this process and will fight to ensure members are consulted as per the law and that you receive every penny you are entitled to”.

“We will fight to ensure Wilko bosses are held accountable for the simple reason our members deserve so much better.

“GMB will not forget the incompetence that has led to this collapse and will we not forget the dividends paid to the millionaires who gambled your jobs on their whims. “

Reacting to the GMB statement, Jonathan Reynolds, Labour’s shadow business secretary, said: “This is devastating news that will likely see stores close across the country. Their loss will have a massive impact on their high streets and my thoughts are with those Wilko staff and their families facing this dreadful news.

“Sadly, shuttered up shops and struggling high streets has become the norm after 13 years of Conservative economic failure.

“Labour has a plan for our high streets. We will tackle the things holding firms back by reforming business rates, cracking down on anti-social behaviour and putting an end to empty premises to bring shoppers back to their high street.”

The family-owned chain, which was established by the Wilkinson family in 1930, had been working with PwC on a search for new investment for several months.

Shortly before it crashed into administration, Sky News revealed that Gordon Brothers, Alteri Investors and Opcapita were examining last-ditch proposals to invest in the business.

Like many high street retailers, it has been hit by inflationary pressures and supply chain challenges.

In recent months, it had been seeking to finalise a company voluntary arrangement (CVA) – a mechanism that would have triggered steep rent cuts at hundreds of stores but avoided any closures.

As recently as late last month, a spokesman for Wilko had described talk of administration as “unfounded”.

The administrators said: “Since our appointment as administrators of Wilko we have held extensive discussions with parties who expressed an interest in buying all or part of the business.

“While discussions continue with those interested in buying parts of the business, it’s clear that the nature of this interest is not focused on the whole group.

“Sadly, it is therefore likely that there will be redundancies and store closures in the future and it has today been necessary to update employee representatives.

“We know this will further add to the uncertainty felt by workers. We will be supporting staff through this deeply unsettling time, working closely with the government, JobCentre plus, unions and large employers to maximise possibilities for a rapid return to work for employees in the event of redundancies.

“In the immediate term, all stores remain open, continue to trade and staff continue to be paid. Contrary to speculation, there are currently no plans to close any stores next week.”

A B&M spokesman declined to comment and a spokesman for Pepco said he would not respond unless a query was emailed.