Kazakhstan and China plan to sign 22 agreements worth around $30 billion, including in the key energy sector, Kazakh President Nursultan Nazarbayev said Saturday after talks with his Chinese counterpart Xi Jinping.

"We've reached an agreement on building an oil refinery which Kazakhstan needs," Nazarbayev told reporters after hosting Xi at his Akorda residence.

The Chinese leader for his part said his country would become a shareholder in the Central Asian country's Kashagan oil field, one of the world's largest.

"An agreement has been reached between the two countries about China's participation in the development of the Kashagan field," he said.

Under the deal, Kazakhstan's state energy company KazMunaiGas is expected sell an 8.33 percent stake in the oil field to state-owned China National Petroleum Corp (CNPC).

Beijing is eagerly eyeing the vast oil and gas resources of ex-Soviet Central Asia for its fast growing domestic economy and is also keen to assert its political influence in the strategically located region.

The two leaders also signed a joint declaration pledging to ramp up their countries' strategic partnership, a term reserved for close allies.

"Today our cooperation is entering a new level," Xi said in a speech at a university in Astana.

"As they say, close neighbours are closer than distant relatives. We assign high priority to our relations with the Central Asian countries."

His visit to Kazakhstan is part of a high-profile four-nation regional tour.

Earlier this week, the Chinese president visited the reclusive energy-rich nation of Turkmenistan where he launched production from the world's second-largest gas field the two countries are developing together.

He is to travel to Uzbekistan and Kyrgyzstan next.