Qatar's state oil company says it has signed a deal that gives China's biggest oil and gas company a 40 per cent stake in drilling rights to an offshore energy exploration zone.

The deal announced Wednesday by Qatar Petroleum allows PetroChina to acquire the rights from France's GDF Suez.

The exploration and production rights cover a drilling area known as Block 4, which includes more than 2,500 square kilometres (965 square miles) near the country's gas-rich North Field. The field is located off the northern coast of Qatar, a peninsula nation jutting into the Gulf.

GDF Suez will retain a 60 per cent stake in the block. Qatar Petroleum says the two companies should begin drilling in the next few months.

Financial terms were not disclosed.