Some 50 international oil companies including Chinese firms have expressed interest in exploration of Ghana's giant Jubilee oilfield, Deputy Energy Minister Kwabena Donkor said on Friday.

Ghana is due to start pumping oil from Jubilee late next year. It is believed to hold between 500 million and 1.8 billion barrels of oil equivalent.

"We have had about 50 companies wanting to invest in the upstream sector of our oil industry," he told reporters.

"Out of this, there are a number of Chinese companies -- China is the single largest investor in the world and we'd have been surprised if they had not approached us," Donkor said.

Donkor added that Ghana has also received offers from U.S. and Scandinavian oil companies, without elaborating.

He said Energy Minister Oteng Adjei was in China on business relating to the energy sector and declined comment on whether the minister's trip had anything to do with Jubilee.

There is speculation Chinese companies could be interested in purchasing a stake in Jubilee held by private investment firm Kosmos Energy and which -- according to sources close to the matter -- Exxon Mobil has already contracted to buy.

Ghana's local GNPC petroleum company is also interested in the asset, GNPC sources have said.