China National Petroleum Corp (CNPC), the country's largest oil and gas producer, has agreed with Kazakh state oil company Kazmunaigas to jointly purchase Kazakh oil company, JSC Mangistaumunaigas (MMG), for $3.3 billion, according to a statement on CNPC's website.

The purchase includes two oil and gas fields and all MMG's other oil and gas assets, the statement said.

MMG owns licenses to explore and develop 15 oil and natural gas fields in Kazakhstan as well as oil fields in the Caspian region. The company's annual crude output stood at 40 million barrels in 2008, and it had 41.8 billion cu m of natural gas reserve.