By David French and Anirban Sen

Citigroup Inc has hired former UBS Group AG banker Dan Ford as a vice chairman within the natural resources and clean energy transition group of its investment bank, according to an internal memo seen by Reuters on Thursday.

Ford has been working with Citi as an external senior advisor over the past year on power, utilities, and renewable energy matters, according to the memo from Michael Jamieson and Sandip Sen, the bank's global heads of natural resources and clean energy transition.

"Dan has made a material impact in deepening client relationships with a number of our corporate clients," Jamieson and Sen said.

A Citi spokesperson declined comment.

Over a 25-year career in banking, Ford has been mainly focused on the power and utilities sector. He previously headed up research coverage of such companies in North America at UBS, per the memo.

Notable energy deals that Citi has advised on this year include Vistra Corp's $3.43 billion acquisition of power generation firm Energy Harbor, as well as Chesapeake Energy Corp's divestiture of some of its oil and gas production assets in South Texas.

(Reporting by Anirban Sen and David French in New York, Editing by Nick Zieminski)