HONG KONG, May 16 (Reuters) - Hong Kong's NWS Holdings Ltd

0659.HK plans to sell its interest in a Macau power supplier to a China state-owned company in a deal worth $612 million, as the transport-to-energy operator focuses on water and related businesses.

NWS said its equally owned joint venture with Suez Environnement Company SEVI.PA had agreed to sell its 90 percent stake in Sino-French Energy Development Co Ltd to Nam Kwong Development, a company under China's State-owned Assets Supervision and Administration Commission.

Macau gambling kingpin Stanley Ho holds the remaining 10 percent of Sino-French Energy, which in turn owns 42.2 percent of Macau electricity supplier Companhia de Electricidade de Macau-CEM, S.A.

As part of the deal, the NWS joint venture will have an option to buy back 9 percent of the stake in Sino-French Energy, NWS said in a filing to the Hong Kong bourse late on Thursday.

NWS, a unit of New World Development Co Ltd 0017.HK , said it expected to book a gain of HK$1.5 billion ($193.50 million)from the disposal. ($1 = 7.7519 Hong Kong Dollars)

(Reporting by Donny Kwok; Editing by Stephen Coates)

((donny.kwok@thomsonreuters.com)(+852 2843 6470)(Reuters Messaging: donny.kwok.reuters.com@reuters.net))

Keywords: NWS MACAU/