The British government said it will use new powers to examine the national security implications of Patrick Drahi, BT Group's biggest shareholder, increasing his stake to 18%.
Business minister Kwasi Kwarteng said today he was exercising his "call-in power" under the National Security and Investment Act 2021 after Drahi's Altice UK raised its shareholding.
The Franco-Israeli entrepreneur bought 12.1% of BT in June last year and raised it to 18% in December but said he did not intend to make a full bid.
It triggered a blunt response from Britain at the time, which warned it would intervene if necessary to protect the telecoms group building the country's critical fibre network.
BT Group said it will fully cooperate with the government review.
The NSI legislation came into force earlier this year, giving the UK government powers to scrutinise and, if necessary, intervene in acquisitions on national security grounds.
Kwarteng now has 30 working days to carry out his assessment.
The BT move is the second time this week the government has exercised the new powers.
The acquisition of Britain's biggest microchip factory Newport Wafer Fab by Chinese-owned technology company Nexperia was called in for a full national security assessment yesterday.
