Harbour Energy has stated that it expects to cut 350 UK onshore jobs, blaming the UK Government's windfall tax.
Since January, the oil and gas extractor has been carrying out a review of its operations, warning that it was re-assessing its future activity in the UK.
The majority of its 1,200 UK onshore staff are based in Aberdeen.
"When we announced the review, we said that as a result of the energy profits levy, which results in an effective tax rate of 75% in the UK regardless of the level of oil and gas prices in the market or realised, we have had to reassess our future activity level in the UK," the company stated.
"At our full year results in March, we explained this would 'lead to a significant reduction in our UK workforce'.
"We are working hard to mitigate the impact of this reduction, by for example, a recruitment freeze and opening a voluntary redundancy scheme."
The figures do not include UK-based corporate and international roles, which are still being reviewed, nor do they include Harbour's offshore organisation, where the impact is expected to be "significantly lower".
A response from the Treasury read: "The Energy Profits Levy strikes a balance between funding cost of living support from excess profits while encouraging investment in order to bolster the UK's energy security.
"We have been clear that we want to encourage reinvestment of the sector's profits to support the economy, jobs, and our energy security, which is why the more investment a firm makes into the UK, the less tax they will pay."
Ryan Crighton, policy director at Aberdeen and Grampian Chamber of Commerce, warned that this move could be the "tip of a terrifying iceberg" for the north east of Scotland.
"Our thoughts are with the 350 people who will be out of work because their industry has been used as a political football.
"Despite repeated warnings about the damage a windfall tax would cause, the UK Government, cheered on by the opposition, chose to take a gamble on the North Sea.
"The chancellor must now wake-up and recognise the corrosive impact the windfall tax has had on jobs and investment and urgently reform the levy to introduce a price floor."
Results released last month revealed that Harbour "delivered materially higher production" and improved margins in 2022, although chief executive Linda Cook said the levy had "disproportionately impacted the UK-focused independent oil and gas companies".
She added at the time: "For Harbour, the UK's largest oil and gas producer, it has all but wiped out our profit for the year... this has driven us to reduce our UK investment and staffing levels".
In 2022, the company reduced its net debt, excluding certain fees, from $2.3bn to $800m.
Harbour distributed $553m to shareholders, while the company proposed a $100m final dividend, alongside a $200m share buyback plan.
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