Wilko, the High Street homeware retailer, has collapsed into administration, putting 12,000 jobs at risk.

The chain has been unable to find emergency investment to save its 400 shops across the UK.

Wilko had been working to find a rescuer for the business which has been trading since 1930.

The firm’s boss, Mark Jackson, said management had “left no stone unturned” in its attempts to save the company.

“But we must concede that with regret, we’ve no choice but to take the difficult decision to enter into administration,” he said.

If a firm fails to buy any of the shops or parts of the business out of administration, Wilko risks becoming the biggest High Street casualty this year.

Administrators are expected to be appointed later on Thursday. It is understood that the business will continue to trade as normal for now.

The GMB union said the collapse was “entirely avoidable”.

National officer Nadine Houghton said: “GMB has been told time and time again how warnings were made that Wilko was in a prime position to capitalise on the growing bargain retailer market, but simply failed to grasp this opportunity.”

Although the business has been struggling for some time, the depths of its problems emerged last week when it announced its intention to appoint administrators.

This gave Wilko 10 days to secure a rescue. However, it was unable to strike a deal within that timeframe.

Mr Jackson said Wilko had received a “significant level of interest” which he said included “indicative offers that we believe would meet all our financial criteria to recapitalise the business”.

But he said: “Without the surety of being able to complete the deal within the necessary time frame and given the cash position, we’ve been left with no choice but to take this unfortunate action.”

Wilko has been struggling with sharp losses and a cash shortage.

The company already borrowed £40m from Hilco, the restructuring specialist. It has previously cut jobs, changed its leadership team and sold off a distribution centre.

Many of Wilko’s stores are in High Street locations in traditional town centres, which became an expensive liability as customers shifted to bigger retail parks and out-of-town locations.

The company has also faced strong competition from rivals such as B&M and The Range as the high cost of living has pushed shoppers to seek out bargains.

Retail analyst Catherine Shuttleworth said the collapse was “sadly inevitable”, adding: “It’s a sad day for the High Street as some of the stores have been a key part of local communities for over 50 years.”

She said that Wilko had failed to adapt the retailer for the future.

“A lack of investment in systems lacking the sophistication to support a business with shops both on High Streets and out of town retail parks combined with a large estate of over 400 stores has meant that significant investments have been needed over the last 10 years and these have simply not been made,” said Ms Shuttleworth.

Richard Lim, chief executive at Retail Economics, a consultancy, said a combination of rising costs, lower customer demand and fierce competition ultimately pushed Wilko to “breaking point”.

“Against the backdrop of seismic shifts in consumer behaviour and the intense pressure on margins, the business was too slow to react to these mounting challenges and paid the ultimate price,” he said.

The company, founded in Leicester, is still owned by the Wilkinson family.

After the collapse of Woolworths in 2008, Wilko stepped up to fill the gaps left on High Streets.

Wilko began home deliveries in the 1940s, and stayed open throughout World War Two, helping residents keep their air raid shelters stocked.

On Wednesday, it announced that it had suspended home deliveries.