"The economic slowdown in China along with ongoing trade tensions is continuing to influence consumer confidence", said JLR Chief Commercial Officer Felix Brautigam.
The threat of Brexit has also intensified as the United Kingdom is set to leave the European Union on 29 March.
"The announcement on job losses will be substantial, affecting managerial, research, sales, design", said the source, who spoke on condition of anonymity, not affecting production-line staff "at this stage".
Speaking ahead of JLR's confirmation, he said: "Given the hard landscape that the automotive industry faces, we were braced for this sort of news".
"What is crucial now is that the Government acts to mitigate against serious repercussions for tier two and three suppliers in the Black Country and across the West Midlands".
Meanwhile, Ford signalled "significant" cuts among its 50,000-strong European workforce under plans to make it more competitive and make its business more sustainable.
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Steven Armstrong, Ford's European group vice president, said the company was taking "decisive action" to transform its European business. The European Union has set lower limits for vehicle carbon dioxide emissions from 2021 that are pushing carmakers to include more electric vehicles in their future sales mix.
Ford said it will seek to exit the family vans or MPV segment, review its operations in Russian Federation, and combine the headquarters of Ford U.K. and Ford Credit to a site in Dunton, Essex to achieve a 6 per cent operating margin in Europe.
Britain's business minister Greg Clark said on Thursday it is clear why a no-deal Brexit would add to the problems with further costs and disruption.
Major Warwick district employer JLR is set to cut up to 5,000 jobs across the UK
AM reported last monmth on reports that JLR would cut up to 5,000 jobs from its work force.
It came as Ford warned that more than 7,000 engine and gearbox manufacturing and development jobs were under threat after the American manufacturer said it was shaking up its European operations.
Unite, the country's largest manufacturing union, said it would be pressing the vehicle maker to safeguard its members' jobs.
"We expect the immediate impact on Ford's United Kingdom operations to be limited".
Most will be in office roles as the company wants to simplify its management structure.
Jaguar Land Rover has been saying for more than a year that Brexit uncertainty would eventually take its toll on the perception of the United Kingdom as a stable and competitive base for global manufacturing.
Beyond the £2.5 billion now being sought, rumours abound that Jaguar could be reincarnated as an all-electric brand in the not-too-distant future, better positioning it to deliver on future customer demand and lessening the burden it now places on the far-healthier Land Rover.
"Britain's auto workers have been caught in the crosshairs of the Government's botched handling of Brexit, mounting economic uncertainty and ministers' demonisation of diesel, which along with the threat of a no-deal Brexit, is damaging consumer confidence".
"The government needs to realise that the automotive sector from factory floor and right across supply chains desperately needs tangible support, not warm words".