According to financial records, the North Sea gas field operated by Russian energy giant Gazprom generated €45m (£39m) in earnings last year. Gazprom has been extracting gas from the Sillimanite field, spanning both UK and Dutch waters, since 2020.

Liberal Democrats leader Sir Ed Davey expressed strong disapproval, deeming it "completely unacceptable" that gas extracted from UK territory was supporting "Putin's unlawful war against Ukraine." In response, the government vowed to escalate economic pressure on Russia.

The Sillimanite field, situated 200km off the Dutch coast, operates as a joint venture between Gazprom and German company Wintershall. The gas extracted is transported to the Netherlands for processing.

While the arrangement is not deemed illegal, the UK, US, and EU have implemented stringent economic sanctions to curtail Russia's ability to profit from energy exports, to hinder funding for the war in Ukraine.

Despite Gazprom executives, including CEO Alexei Miller, being under UK sanctions, the company itself remains unaffected. Gazprom continues to supply gas to continental Europe through pipelines, although at reduced volumes since the onset of the conflict.

Financial reports disclose that Gazprom International UK, a Gazprom subsidiary, achieved a pre-tax profit of €45m in 2022. It distributed a €41m dividend to Gazprom International Projects BV, its immediate owner in the Netherlands, and an additional €1.7m dividend in June of the same year. The ultimate owner is Moscow-based PJSC Gazprom.

As a major contributor to Russia's finances, Gazprom, predominantly owned by the Russian state, has provided $80bn (£63bn) in taxes to the Russian government, as reported by the state news agency TASS.

The company has also played a role in recruiting and financing militias involved in frontline fighting in Ukraine.

Sir Ed, a former energy secretary, emphasized the intolerability of gas extracted from UK territory supporting Putin's war efforts in Ukraine.

Campaign group Global Witness called it "an indictment of the UK's approach to Russian oil and gas".

"Whilst the government decries the war, it's absurd to allow the subsidiary of a Russian state enterprise which has its militia fighting in Ukraine to enrich Putin's regime from the North Sea," it added.

A government spokesman said it would "continue to work alongside our partners to deny Russia access to any of our goods or technologies that it could use in its war machine, restricting Russia's ability to fight a 21st-century war".

"Putin and his supporters must - and will - pay the price for their illegal invasion of Ukraine," he added.

"We will continue to ratchet up economic pressure and come down hard on all emerging forms of circumvention until Ukraine prevails and peace is secured."

The company's total tax bill was €29m, divided between the UK and Dutch governments. This includes €4m under the UK windfall tax imposed on energy companies after prices surged following the war in Ukraine, and €5m under the Dutch equivalent.

All of Gazprom International UK's revenues are from sales outside the UK, the accounts say. The company ended its agreement to sell gas to Wintershall in September this year, and replaced it by an agreement to sell gas to the Swiss-based trading company Gunvor, the accounts show.

Gazprom's UK energy supply business, which had thousands of business customers, was nationalized by the German government last year when its parent company was close to bankruptcy. It has been renamed SEFE Energy.

Wintershall and Gazprom did not respond to the BBC's requests for comment.

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