PetroChina Co Ltd, the country's largest oil producer, has finalized an agreement with the United States-based energy giant Exxon Mobil Corp to buy a 25 percent stake in Iraq's West Qurna 1 oilfield, PetroChina said on Thursday.

The cooperation project between the world's top listed oil companies will further boost the Chinese giant's already strong presence in Iraq's oil industry.

Participating in the project will allow PetroChina to expand its upstream businesses in the Middle East and is significant for the company's development in the high-end oil market, PetroChina said in a statement.