North Korea's state media said Sunday that it has lifted the quarantine placed on some 3,600 people over new coronavirus concerns.

Around 3,650 people under quarantine have been released as of Thursday, including some 1,020 in Kangwon Province and 2,630 in Chagang Province, according to the North's radio broadcaster, the Korean Central Broadcasting Station.

In mid-February, North Korea doubled the quarantine period for people at risk of being exposed to the virus to a month as it stepped up anti-virus efforts across the country.

The North has not reported any confirmed coronavirus infections, but speculation persists that it might be concealing an outbreak that is possibly spiraling out of control.

North Korea could be vulnerable as it shares a long and porous border with China and lacks key medical supplies and infrastructure to test and treat infected people.

The North's official Korean Central News Agency said earlier on Friday that the country released 221 out of 380 foreigners who were held in quarantine.

Foreign diplomats in Pyongyang were also released earlier last week after a month of isolation as part of efforts to prevent the virus, media reports said.

At least 7,000 people in the North are known to be under quarantine or medical monitoring for apparently showing symptoms of the novel coronavirus, according to reports.