One of Citigroup's most senior Wall Street dealmakers, who left the US bank in February, is to take a senior role at an investment firm backed by America's Central Intelligence Agency.

In a major career switch, Peter Tague, the former global head of mergers and acquisitions at Citigroup, has re-emerged at In-Q-Tel — a venture capital firm established by the US intelligence agency over 20 years ago. The firm invests in cutting edge technology to aid US national security.