The subsidiaries, the foremost of which is The Oman 91ºÚÁÏÍø Company (TOCO), will be owned 85% by Interserve and 15% by its Omani partner.
The total cash consideration is US$41.3m (£24.9m) for the deal.
Interserve CEO Adrian Ringrose said: “Interserve sees the Middle East oil and gas sector as a key growth market and this acquisition further develops our presence in the region. As part of Interserve, we believe TOCO's growth will be accelerated through innovation, enhanced business development and a number of operational efficiencies."
 The acquired gross assets of the subsidiaries are about US$31m, including cash of approximately US$4m. The unaudited pre-tax profits of the subsidiaries for the 10-month period to the 31 October 2012 were approximately US$6m.
Interserve is acquiring the businesses from Willbros International Finance & Equipment Limited, a subsidiary of Willbros Group Inc, the US listed oil and gas services company.
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