China's CITIC Group announced on Sunday that it has successfully acquired the Kazakhstan oil assets of Canada's Nations Energy Company Ltd for US$1.91 billion.

This is the third largest overseas oil acquisition made by Chinese companies.

The deal has made CITIC to acquire a 100 percent interest of Nations Energy, after the Canadian company sold off its non-Kazakhstan assets according to an agreement signed in October.

The acquisition allows CITIC to develop the Karazhanbas oil and gas field in Mangistau Oblast, Kazakhstan until 2020. It has proven reserves in excess of 340 million barrels of oil and it currently produces over 50,000 barrels of oil a day.

Pursuant to the approval received from the Kazakhstan regulatory authorities for CITIC's acquisition, CITIC has granted to KazMunaiGas (KMG), the state-owned oil company of the Republic of Kazakhstan, a call option under which KMG may acquire a 50 percent interest in Nations Energy.

The option is exercisable within a one-year period and the price is based on CITIC's acquisition price for Nations Energy, said CITIC.

Nations Energy's Kazakhstan oil assets also include a 100 percent interest in Argymak Trans Service LLP which provides transportation services and Tulpar Munai Services LLP which provides drilling, workover and training services.

"We will focus on cooperating with Nations Energy's current oil customers, suppliers and partners but there are no clear plans to sell oil to China," said an insider with the deal earlier, who would only give his surname Lu.

The deal will help CITIC develop its petroleum and natural gas business, said Kong Dan, chairman of the CITIC Group.

"It will provide CITIC with an important base from which it can expand its energy business in Kazakhstan, the most important petroleum producer in Central Asia," Kong said.

He said the takeover is also a good opportunity for the CITIC to diversify its investments and business in Kazakhstan.

CITIC said earlier that it is also planning a feasibility study on developing local oil refining and is looking for partners in other sectors such as construction and financing.