HONG KONG, Aug 28 (Reuters) - China has signed an initial agreement with Hong Kong to guarantee a steady supply of energy to the city for a further 20 years under a broad plan to cut the use of polluting coal and raise that of cleaner energy sources.

Under the pact, a liquefied natural gas terminal will be jointly built on the mainland to supply gas to Hong Kong, potentially supplanting a similar project by CLP 0002.HK, Hong Kong's largest electricity producer.

“The main purpose of the MOU is that in the future there will be a long-term, stable supply of energy to Hong Kong,” Secretary for the Environment Edward Yau told reporters on Thursday.

“What is important is we do not need anymore to build LNG terminals in Hong Kong. So there will be no more pressure for hiking tariffs as a result of investment. This is good news for consumers.”

He did not specify when or where the terminal would be built.

CLP is seeking Hong Kong government approval to build a HK$8 billion LNG terminal in the city to replace its depleting natural gas field in the South China Sea.

Yau also said a study will also be conducted on the feasibility of PetroChina 0857.HKPTR.N601857.SS supplying natural gas to Hong Kong through a second West-East pipeline.

Under the agreement, top Chinese offshore oil firm China National Offshore Oil Corporation, parent of CNOOC Ltd 0883.HKCEO.N, will renew an agreement to supply natural gas to Hong Kong for 20 years, both governments said.

China Guangdong Nuclear Power Holding Co Ltd will renew its supply agreement to Hong Kong for another 20 years. The quantity supplied will not be less than current levels, they added.

Looking ahead, Yau said Hong Kong hoped to increase the proportion of natural gas in its energy mix.

“There is a strong inclination among the community to increase the proportion of natural gas...to about half, subject of course to availability of gas in the medium- and long-term,” he said.

Hong Kong now depends on coal for 60 percent of its energy needs, while natural gas and nuclear each accounts for 20 percent.