March 26 (Reuters) - British engineering company Smiths Group named insider Roland Carter as its new chief executive officer on Tuesday, succeeding Paul Keel who will step down with immediate effect.

Carter most recently led the company's unit that makes security screening systems - Smiths Detection. Before this, he was involved with the setting up of Smiths' joint venture in China as its head of Asia-Pacific.

Keel, who is stepping down to take on a role as CEO of a U.S. public company, took the top job at Smiths in 2021.

Separately, Smiths also reported a 5.3% organic rise in half-year operating profit and announced a new 100 million pound ($126.51 million) share buyback programme.

($1 = 0.7905 pounds) (Reporting by Eva Mathews in Bengaluru; Editing by Eileen Soreng)