But concerns are growing about the impact of the stoppage on the carmaker's extensive supply chain, amid claims some companies could face bankruptcy without prompt financial support.

The shutdown is believed to be costing the company at least £50m a week in lost production. JLR would normally expect to build more than 1,000 cars a day.

The firm, which is owned by India's Tata Motors, has car plants in Solihull and Halewood, as well as an engine facility in Wolverhampton.

It also has large factories in Slovakia and China, as well as a smaller facility in India.

But all of the production lines have been at a standstill since 1 September when the hack first came to light.

Announcing the latest delay, JLR said: "We have taken this decision as our forensic investigation of the cyber incident continues and as we consider the different stages of the controlled restart of our global operations, which will take time.

"We are very sorry for the continued disruption this incident is causing and we will continue to update as the investigation progresses."

JLR initially appeared confident that the situation would be resolved quickly. However, it has since become clear that restarting production is not a simple process.

The company has admitted some data may have been viewed or stolen by third parties as a result of the cyber attack.

By 24 September, three and a half weeks of output will have been lost. Industry insiders say that even once the production lines have restarted, getting back to normal output is likely to take several weeks.

Among suppliers, many of whom are small and medium sized businesses, there is growing concern.

Several have told the BBC they simply do not have the financial resources to cope with an extended shutdown and industry experts have said bankruptcies are likely, unless some kind of support is provided.

Jason Richards, West Midlands regional officer at Unite the union, told the BBC: "We're already seeing employers having discussions on potential redundancies. People have to pay rent, they have to pay mortgages and if they're not getting any pay, what are they supposed to do?

"We need to have a supply chain into Jaguar Land Rover. I can't emphasise it enough [because] if they turn the tap on and they're expecting the supply chain to be waiting on the subs bench, they won't be there," he added.

JLR could face disruption until November, claim sources