China National Petroleum Corp., the country’s largest oil producer, will spend $4.2 billion for a stake in Italian energy giant Eni SpA (ENI)’s African natural-gas assets as China looks to feed energy demand while reducing its reliance on coal, Bloomberg said.

CNPC will buy a 20 percent stake in Mozambique’s Area 4 where 75 trillion cubic feet of gas, or more than Norway’s existing reserves, has been found, state-controlled CNPC said in a statement on its website yesterday.

The purchase will be the biggest deal involving an Asian company announced this year and CNPC’s largest overseas purchase ever, according to data compiled by Bloomberg. China’s oil companies have bought oil and gas fields in countries ranging from Australia to Canada to Nigeria to meet energy demand in the world’s fastest-growing major economy.

“This acquisition affirms China’s insatiable appetite for environmentally friendly natural gas projects, paving the way for more domestic natural gas pricing adjustments ahead,” said Gordon Kwan, head of energy research at Mirae Asset Securities Ltd. in Hong Kong. “Coal will slowly lose market share in China in the coming decade.”

Pollution in Beijing rose to a record on Jan. 12, sparking criticism of the government’s management of the environment.

Mozambique may have 250 trillion cubic feet of reserves, according to Empresa Nacional de Hidrocarbonetos, the country’s state-backed petroleum exploration company. ENH, Galp Energia SGPS and Korea Gas Corp. each own 10 percent of Area 4, according to the statement.