Engineering and technology firm Smiths Group has reported a 4% fall in underlying profits for the financial year on the back of "significant headwinds" in the global energy market. Operating profit came in at £510m ($664m) for the 12 months ended 31 July.

This was mainly because of a 20% drop in operating profit at US subsidiary John Crane, which manufactures equipment used by oil companies and refiners.

Total underlying revenue fell 2% year-on-year to £2.95bn.

"Smiths Group delivered a robust performance this year. We achieved good growth in headline operating profits with associated margin expansion in our Medical, Detection and Interconnect divisions, driven by revenue growth and business improvement initiatives," Smiths chief executive Andy Reynolds Smith said in a statement.

"However, significant headwinds in the global energy markets impacted John Crane, primarily in the sales of first-fit equipment."

Smiths Group comprises five divisions: Smiths Detection, Smiths Medical, John Crane, Smiths Interconnect and Flex-Tek.

The company, which started out as a watch-making business in London in 1851, has operations in over 50 countries, and employs over 23,000 staff.