China may grant Russian state-owned oil giant Rosneft a loan to boost China-bound oil supplies, Deputy Prime Minister Arkady Dvorkovich said on Wednesday, but did not say how much cash might be involved.

"A loan is not ruled out [to be given by the Chinese side for Rosneft's increased oil supplies]. Rosneft discussed this issue with a corresponding Chinese bank," Dvorkovich said.

Rosneft and oil pipeline monopoly Transneft currently deliver 15 million tons of crude to China annually via a Russia-China branch of the East Siberia–Pacific Ocean pipeline under a 20-year deal signed in 2009. Deliveries started in 2011.

Rosneft received $15 billion and Transneft $10 billion in loans from Chinese banks in 2009, in return for long-term crude supplies.

Dvorkovich said on Monday Rosneft may increase oil supplies to China by over 9 million metric tons to help supply a projected joint refinery project in the Chinese city of Tianjin in northern China.

"So far, specific parameters have not been defined, but in any case deliveries should be sufficient to implement the Tianjin refinery project. This is about 9 million tons of oil and the Chinese side is interested in an even bigger increase in deliveries," Dvorkovich said at the time.

A firm deal is expected to be ready in time for a visit by new Chinese leader Xi Jinping to Moscow in late March, his first visit to a foreign capital as president, Dvorkovich said.

An oil industry source previously told Prime news agency Rosneft was considering supplying crude to China via the Atasu-Alashankou pipeline through Kazakhstan

Reuters news agency reported in mid-February Rosneft was negotiating to raise as much as $30 billion from China's CNPC. A Rosneft representative later denied these reports.

Rosneft is once again cash-hungry as it absorbs the cost of buying up TNK-BP, the Russo-British joint venture, which is costing it over $50 billion.