The UK government is poised to water down its 2030 targets for electric vehicle sales after intensive lobbying by the car industry and unions.

The government is preparing to consult on less ambitious targets for the transition to fully battery-powered electric cars over the rest of the decade after carmakers and unions warned that they would penalise manufacturers and put jobs at risk.

Hybrid vehicles could be allowed to make up a far bigger proportion of the UK’s car sales in the medium term by softening the mandate for pure electric cars from 80% of all sales by 2030 to 50%.

Government sources stressed that the 2030 ban on the sale of new purely petrol or diesel cars would still apply, meaning 50% of car sales would be hybrid electric. The government’s 2035 deadline for phasing out new hybrid cars is understood to remain in place.

The government’s electric vehicle targets, known as the zero emission vehicle (ZEV) mandate, were first introduced under the Conservatives in 2023 to force carmakers to increase sales of electric cars up to 80% by 2030.

The latest proposed change would mark the second time since coming to power that the Labour government has weakened the rules by allowing carmakers to sell more hybrid vehicles.

Ministers tweaked the mandate rules last year to allow prolonged sales of plug-in hybrid cars – which have petrol engines and a small battery – in a move that campaigners warned would significantly drive up emissions. Just under 14% of sales are now of plug-in hybrid models.

The government had already committed to review the mandates again in 2027 but is now set to bring that forward. According to a report in the Sunday Times, the prime minister, Keir Starmer, has opted to back the business secretary, Peter Kyle, in weakening the mandate rather than sticking to net zero targets as urged by the energy secretary, Ed Miliband.

Electric vehicle sales are increasing steadily but continue to lag behind the government’s targets after initial years of rapid growth. In May, 27.3% of UK new car registrations were battery electric, below the 33% mandate for 2026 sales. Manufacturers have said they are having to discount heavily to boost sales of EVs, whose production costs have not yet fallen as fast as anticipated.

Under the ZEV mandate carmakers are credited for electric car sales but face fines if they do not reach the annually growing proportion of EVs compared with petrol and diesel sales.

According to the Unite union, which has campaigned to review the targets, the mandate could cost up to £11,000 in fines per vehicle and threaten jobs in the sector in the UK.

The Unite general secretary, Sharon Graham, described the reported change as a “huge victory”, saying car workers had been increasingly fearful for their jobs.

She said: “The failure to act would have been an act of self-harm to a sector which is a jewel in the crown of UK manufacturing. The consultation must be swiftly concluded and its findings quickly implemented to provide the sector and workers with much-needed certainty.”

The car industry body the Society of Motor Manufacturers and Traders declined to comment.

However, others reacted with dismay at the news. Businesses in the EV charging sector in particular have stressed the need to keep the mandates in place to drive change.

James Alexander, the chief executive of the UK Sustainable Investment and Finance Association, said: “Investors have been absolutely clear that the ZEV mandate is vital for driving investment into our charging infrastructure. Any attempt to water down these targets could send warning signals about the government’s long-term commitment to electrifying our transport network.”

Vicky Read, the chief executive of ChargeUK, which represents charging companies, said it was astonishing that Starmer would consider weakening the mandate again, warning that it would “slam the brakes on infrastructure rollout and send the entire transition into a tailspin”.

The Transport & Environment thinktank warned that the industry lobbying for weaker mandates would backfire in the long term. The T&E UK director, Anna Krajinska, said: “This policy is what’s driving billions in investment – from manufacturers to EV charging – to future-proof the auto industry as global markets go electric. Pulling back again now would send a clear signal that the UK is not serious about competing in the global EV race or having an auto industry.”