(Bloomberg) -- The UK is examining French telecom tycoon Patrick Drahi’s 18% stake in BT Group Plc citing national security concerns, the British phone company said Thursday. 

Business secretary Kwasi Kwarteng will review Drahi’s investment in the former state-owned telecommunications monopoly after his investment vehicle Altice UK increased its stake in BT from 12.1% to 18% in December. 

Drahi’s stake in BT has fueled speculation since he revealed his stake last year, sparking concerns about a takeover attempt, or so-called creeping control. The billionaire has previously insisted he doesn’t intend to make an imminent takeover bid, triggering six-month standstills under British takeover law. The second of those expires in June.

It’s the second roll-out in 24 hours of the new National Security and Investment Act, which came into force Jan. 4 after Kwarteng referred a Chinese-led takeover of a British semiconductor firm for an in-depth probe on Wednesday. 

Officials now have 30 working days to carry out an assessment, under the law -- though they can extend that timeline by another 45 days if deemed necessary. 

A spokesman for Altice did not immediately respond to a request for comment

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