March 18 (Reuters) - British engineer Smiths Group Plc reported a 5 percent fall in first-half operating profit and said it appointed Rob White as interim chief financial officer effective April 25.

White replaces Peter Turner, who stepped down as finance director in October.

The company, which makes industrial seals, medical devices and security detectors, said headline operating profit fell to 232 million pounds ($342 million) in the six months ended Jan. 31 from 245 million pounds a year earlier.

($1 = 0.6781 pounds) (Reporting by Esha Vaish and Roshni Menon in Bengaluru; Editing by Gopakumar Warrier)