Recent satellite imagery shows an "unusual" level of aircraft maintenance at North Korea's main airport, a monitoring group said, a possible sign Pyongyang is moving to resume international flights.
North Korea has effectively sealed its borders since early 2020 as part of its drive to deal with the coronavirus pandemic, with all flights cancelled.
It has resumed some cross-border trade with China by train, and recently allowed Beijing's new ambassador to Pyongyang into the country, but has not yet resumed regular international travel.
Several passenger jets operated by North Korea's Air Koryo have "cycled through maintenance hangars" at Sunan International Airport since early May, the respected North Korea-monitoring 38North website said, citing satellite images.
Such aircraft have only very infrequently undergone such maintenance over the past three years, so the recent level of activity is "notable", it said.
38North said no cross-border air travel service is "believed to have taken place" throughout the entire pandemic period.
"It is unusual that such a large number have been serviced in such a short period of time," 38 North said, warning that the flurry of activity did not guarantee any immediate or near-term resumption of air travel.
Speculation over Pyongyang's possible reopening spiked after China's new ambassador arrived in Pyongyang to begin his official duties last month, more than two years after he was appointed.
One Chinese tourist agency has also been reportedly preparing to re-launch tours to North Korea in mid-June, according to the Seoul-based specialist site NK News.
It added, however, that "false rumours of reopening have circulated near border for months".
Other diplomats from countries with presences in North Korea told NK News they had not had any news about being able to rotate staff in or out of Pyongyang.
"Global tours are one area where Pyongyang has always taken great interest, because it can easily cash out foreign currency," Hong Min, researcher at the Korea Institute for National Unification, told AFP.
He said it did not seem "far-fetched" that some tour services could resume this year.
