Mexican billionaire Carlos Slim has snapped up a three percent stake in UK telco BT.

Slim acquired the stake, worth £400 million ($511m), through financial holding company Inbursa and its subsidiaries, which are controlled by the family of the businessman.

Slim joins becomes the latest foreign investor in the company after French billionaire Patrick Drahi, owner of French telco Altice, who has built a 24.5 percent stake in BT.

In 2015, Deutsche Telekom acquired a 12.5 percent stake in BT however, the company's CEO Tim Höttges has since said the acquisition has been the company's "biggest mistake."

Slim, who was once the world's richest man, built his fortune via a 1990s concession for Mexico’s state telephone company.

His group controls América Móvil, and has also previously acquired stakes in European telecoms groups KPN and Telekom Austria.

The investment comes a week after BT's new CEO Allison Kirkby announced plans to target a further £3 billion ($3.85bn) in cost savings by 2029.

BT said it had achieved its first cost savings target of £3bn ($3.79bn) during this period, a year earlier than initially expected.

Last year, BT announced plans to cut 55,000 jobs by the end of the decade, affecting its operations both in the UK and globally. At the time, BT noted that its workforce was around 130,000.