Train journeys between the two countries were halted in 2020 as they imposed strict border closures to prevent the coronavirus from spreading.

While China has since fully reopened its borders, North Korea has proceeded more slowly, though direct flights and train services with Russia resumed last year.

But travel agents for an official ticketing booth in Beijing told AFP on Tuesday that anyone with a valid visa was now able to buy train tickets to the diplomatically isolated nation.

This would include Chinese people working and studying in North Korea, as well as North Koreans working, studying and visiting family abroad.

Another such ticketing booth in the Chinese border city of Dandong told AFP that sales would resume on Wednesday but tourists were not yet eligible to buy tickets.

"It's great to see the international train service resuming," Rowan Beard, tours manager at Young Pioneer Tours, told AFP.

He confirmed his company, one of several foreign-run firms that specialises in travel to North Korea, could also organise tickets from Thursday.

"While it isn't initially intended for tourists, it will provide another travel option once tourism to North Korea eventually returns, serving as an alternative to flying," Beard said.

Simon Cockerell, general manager of Koryo Tours, sounded a note of caution.

"This has been announced before and it's been untrue, but this time does seem a bit more legitimate," he told AFP.

If true, "this is a good step for sure", he said.

South Korea's Unification Ministry said in a statement that "we understand that the Pyongyang-Beijing international train service is set to resume operations on March 12, and we will continue to closely monitor related developments".

China's foreign ministry spokesman Guo Jiakun did not confirm the reports when asked by reporters at a press briefing on Tuesday.

"Maintaining regular passenger train services is of great significance in facilitating people-to-people exchanges between the two sides," he said.

Despite periods of strained relations between China and North Korea over Pyongyang's nuclear programme, the two neighbours have maintained close ties.

China is historically North Korea's biggest backer and a crucial lifeline for its moribund economy, though Pyongyang has drawn closer to Russia since the start of the Ukraine war.

North Korea's reclusive authorities have given mixed signals on whether further opening is on the cards.

On Monday, Koryo Tours said North Korea had cancelled an international marathon in its capital Pyongyang originally scheduled for early next month, citing an official statement with no explanation for the decision.

The cancellation was "unexpected", the company said, adding it understood the decision had been "taken at a level above the organisers of the event itself".

The marathon is the largest international sporting event in North Korea, offering visitors a rare chance to run through Pyongyang's tightly controlled streets.