Russia will continue helping fuel-hungry Cuba with crucial supplies of oil, Foreign Minister Sergei Lavrov said on Wednesday, two weeks after Moscow sent a tanker with around 700,000 barrels of crude to the Caribbean island.

Washington stopped oil exports ​to Cuba from its main ally Venezuela after capturing Venezuelan President Nicolas Maduro on January 3, triggering acute fuel shortages across the communist-ruled island of almost 11 million people.

President Donald Trump has threatened punishing tariffs on countries sending crude to Cuba as he seeks to put pressure on the government. The US later allowed the Russian oil delivery to Cuba, this year's first by Moscow, for humanitarian reasons.

Another major supplier, Mexico, halted its shipments.

Lavrov, on a visit to China, said Russia will provide humanitarian aid to Cuba, its long-standing ally.

"We have dispatched the first tanker with 100,000 tons (700,000 barrels) of oil for Cuba. Of course, this will probably last for a couple of months - I'm not a specialist," he told a briefing at the end of the two-day visit.

"But I have no doubt that we will continue providing such assistance, and that (China) will, of course, continue to take part in this cooperation as well," added Lavrov, without referring to the issue of US permission or not for future deliveries.

Cuba produces less than a third of the oil it requires. Though it cleared the recent Russian delivery, the Trump administration said it would review further oil shipments to Cuba on a "case-by-case" basis.

Lavrov said he hoped the US will not return to times of "colonial wars."