Turkmenistan's oil and gas ministry has accused Russian state gas company Gazprom of failing to pay for deliveries in a sign of friction between the two major gas producers.

The Central Asian nation's ministry said in a statement that Gazprom "has failed to pay under its contracts for buying and selling natural gas" since the start of the year. Global economic problems and international sanctions against Russia are the cause, the ministry said.

Over the last decade, Russia has dramatically reduced its reliance on gas from Turkmenistan, which has become a major supplier to China.

Turkmenistan plans to build a pipeline under the Caspian Sea to gain access to European markets, but political rivalries have dogged the project and construction is yet to begin.