Following the sale, the new ownership structure for the block will see Total have 45 percent, Qatar Petroleum 25 percent, CNR International 20 percent and Main Street will own 10 percent, Total and QP said in statements.

"This agreement is another step by Qatar Petroleum ... in expanding and reinforcing Qatar's leading position in the field of energy across the globe," QP's Chief Executive Saad al-Kaabi said, adding that the drilling of an exploration well is planned this year.

The agreement comes at a sensitive time for Doha, which is in the midst of a protracted crisis with its Gulf neighbours.

OPEC kingpin Saudi Arabia and the United Arab Emirates cut ties with Doha in June, saying Qatar backed terrorism and was cosying up to rival Iran. Qatar rejected the accusations.

But despite the rift, US and European oil majors are piling in with offers to help Qatar develop new gas projects, the country's energy minister told Reuters last month.

Qatar seeks to expand its gas capacity to 100 million tonnes a year from the current 77 million to cement its position as the world's largest exporter of liquefied natural gas (LNG).

Reuters reported last year that Qatar's traditional partners Exxon Mobil, Royal Dutch Shell and Total, which helped turn the country into a gas superpower, had all shown interest in new projects.

Total is seen as a front-runner to pick up more LNG business in Qatar, and opening an opportunity for QP to join its global operations would strengthen the French major's position.

Exploration Block 11B/12B is located in the Outeniqua Basin, around 175 km off the southern coast of South Africa, and covers an area of 19,000 square kilometres with water depths ranging from 200 to 1,800 metres.