At two state-owned gas stations in the Central Asian country's capital Ashgabat, highly subsidised prices for 95-octane petrol rose overnight from one manat ($0.29) per litre to 1.5 manats per litre, an AFP correspondent saw.

The cost of 92-octane petrol saw a similar overnight spike, going from 0.94 manats to 1.35 manats.

Turkmenistan's petrol stations are all state-owned and prices do not vary.

The US dollar equals 3.5 manats according to the official exchange rate but the dollar can fetch more than 9 manats on the black market, reflecting the weakness of local currency and strong government restrictions on foreign exchange.

Turkmen President Gurbanguly Berdymukhamedov said in his annual state address last month that the country's economy grew 6.5 percent last year but economic data in Turkmenistan is notoriously difficult to verify.

Hydrocarbons account for over 90 percent of the majority-Muslim country's exports. China replaced Russia as the country's main buyer of natural gas at the beginning of this decade.

Low global energy prices in recent years have forced the authoritarian government to hike tariffs for electricity and water that were provided free of charge to the public under Berdymukhamedov's late predecessor Saparmurat Niyazov.

Cheap living costs have long been seen as a form of compensation for citizens in a country where they enjoy few meaningful rights and information is strictly controlled.

Under Niyazov, petrol was also very cheap, costing the equivalent of just two US cents per litre in 1993, two years after the country gained independence from the former Soviet Union.

Shortly after coming to the power following Niyazov's sudden death in 2006, former dentist Berdymukhamedov allowed every car owner 120 litres of free petrol per month, but scrapped the policy in 2014.

Both men are honoured by golden statues in Ashgabat, where natural gas wealth is flaunted in lavish, grandiose white marble architecture, even as other parts of the country suffer from poverty.