Clifford Chance (CC), Linklaters and Simpson Thacher & Bartlett have taken roles on KKR's acquisition of UK oil and gas company Acteon, in a deal valued at around £800m.

The transaction has seen energy-focused private equity group First Reserve sell its 52% stake in the company to US buyout giant KKR.

US firm Simpson advised on aspects of the transaction on both sides, separated by a Chinese wall. The firm's US arm assisted longstanding client First Reserve, with New York-based M&A partner Bill Curbow tax partner John Creed and litigation partner David Vann at the helm.

Simpson also advised KKR on debt and equity arrangements, with a London-based team comprising acquisition finance partner Ian Barratt and M&A and capital markets partner Alvaro Gomez de Membrillera Galiana.

The firm was instructed alongside CC, which advised longstanding client KKR on sale and purchase aspects with a team led by corporate finance partner Kem Ihenacho.

Acteon specialises in providing sub-sea engineering services and products. The company's management team was advised by Scots law firm Paull & Williamsons with a team headed up by Aberdeen corporate partner Jamie Stark, while Linklaters advised the banks with a team led by London leveraged finance co-head Nick Syson.

SJ Berwin also took a role on the deal, advising Acteon's management on their new equity arrangements with KKR. The firm's team was led by corporate finance head Steven Davis.

The deal is expected to close by the end of the year, subject to regulatory approval.

Simpson Thacher has longstanding ties to KKR and has advised on a raft of deals for the private equity giant including its 2010 purchase of Pets at Home from Bridgepoint Capital.