A Russian military plane carrying medical equipment has departed for the United States, the defence ministry in Moscow said Wednesday, as the Kremlin flexes its soft power amid the coronavirus pandemic.

The Antonov-124, "with medical masks and medical equipment on board", left for the US overnight, a statement said, without providing further details.

Video released by the ministry showed the cargo plane loaded with boxes preparing to take off from a military airbase near Moscow early Wednesday morning.

Contacted by AFP, the defence ministry refused to provide any further information on the delivery, which came after Russian President Vladimir Putin spoke with US counterpart Donald Trump on Monday.

Russia has previously sent medical supplies and experts to coronavirus-hit Italy as part of a humanitarian effort that analysts said carried geopolitical overtones.

Moscow said the aid for Italy included some 100 virus specialists with experience dealing with Ebola and swine fever, but Italian media have reported that much of the aid was not useful in the fight against the virus.

Last month, Russia said it had sent nearly 1,000 coronavirus testing kits to ex-Soviet states and countries including Iran and North Korea.

The US now has 188,663 confirmed coronavirus cases, by far the highest of any country, according to a Johns Hopkins tally, and more than 4,000 deaths.

Kremlin spokesperson Dmitry Peskov said on Tuesday that Putin expected the US to return the gesture if Russia faces a similar crisis and US producers have increased their capacity to produce medical supplies.

"Today, when the situation touches absolutely everyone and is of a global nature, there is no alternative to acting together in the spirit of partnership and mutual assistance," he said.

Trump said earlier this week that "Russia sent us a very, very large planeload of things, medical equipment, which was very nice."

Health officials in Russia have registered a sharp increase in the number of infections, with 2,337 cases and 17 deaths confirmed, according to the latest figures Wednesday.