Seoul, May 9 (IANS): North Korea on Monday again called for stepped-up efforts to prevent the spread of Covid-19 amid speculation of a possible outbreak in the country which has claimed to be free of the virus.

South Korea's spy agency said earlier that a temporary lockdown imposed in the North on May 4 is suspected to have been related to Covid-19, though it also raised the possibility of an outbreak of waterborne diseases, such as typhoid, reports Yonhap News Agency reported.

North Korea's Rodong Sinmun newspaper urged people not to let their guard down and stressed that even a single violation of anti-virus measures can bring down the whole quarantine system the country has built.

"Our most dangerous enemy right now, at a time when emergency anti-virus efforts have protracted, is inattentiveness and laxity," the paper said.

The North has implemented relatively swift measures to ward off the pandemic since January 2020, including border controls of people and goods between Pyongyang and China.

Last month, freight train operations on a route between the Chinese city of Dandong and the North Korean border city of Sinuiju were apparently suspended amid the spread of the virus in China, after it resumed operations in January after more than a year.