Britain has launched an investigation into a leak from National Security Council discussions on the possible use of U.K. military bases by the United States in a war with Iran, a senior official said Tuesday.

Cabinet Secretary and Head of the Civil Service Dame Antonia Romeo said an investigation is underway about unauthorized disclosure of proceedings of the National Security Council.

"I can confirm that the Government Security Group is conducting an inquiry into this unauthorized disclosure, which draws on the full range of powers at their disposal," she said.

Romeo confirmed the investigation in a letter to Conservative Party lawmaker Alex Burghart over his question about the proceedings related to the incident.

This came after previous reports suggested that Prime Minister Keir Starmer suggested allowing the U.S. to use the bases to carry out defensive strikes against Iranian targets at the meeting but was met with opposition from some Cabinet members, including U.K. Energy Minister Ed Miliband who led calls to stop the U.S. from using British military bases for its initial action against Iran in early March.

The U.K. later gave permission to the U.S. to use its bases amid strained ties.

U.S.-Israeli attacks on Iran have so far killed more than 1,200 people, including Supreme Leader Ali Khamenei.

Iran has retaliated with drone and missile strikes targeting Israel, Jordan, Iraq and Gulf countries hosting U.S. military assets.