North Korea has reportedly resumed transmitting coded messages across South Korea airwaves, even as tensions rise amid fears that the hermit kingdom may be working to conduct a sixth nuclear test. On Friday (12 May) at around 1.15 am local time, Pyongyang's state radio broadcast mysterious numerical coded messages across rival South's airwaves, according to reports.

Pyongyang's latest broadcasts come just days after South Korean elections, which saw former human rights lawyer Moon Jae-in elected as the country's new president. The broadcast also comes amid growing fears of a potential World War 3 erupting as tensions among North Korea, US and China continue to escalate.

Yonhap reported that North Korea's latest radio broadcast involved a female announcer reading out random numbers such as "No. 18 on Page 451." The announcer reportedly said that she was "giving review work in foreign language lessons of the remote education university for No. 27 expedition agents."

Reports speculate that the messages may be secret instructions to North Korean spies across the border. This theory has not been independently verified by IBTimes UK.

Yonhap reported that the radio broadcasts are remnants from a Cold-War era campaign, which saw the hermit kingdom secretly instructing its agents in South Korea. Although the practice was reportedly suspended in 2000 when the two rival nations held a historic summit, North Korea reportedly resumed the radio broadcasts last June.

Yonhap cited espionage experts as being divided on the nature of the radio messages. While some believe the broadcasts may be the Kim Jong-un led nation's efforts to relay instructions to spies for espionage missions, others said that this may just be a deceptive strategy aimed at fuelling further tensions within South Korea.

"It is hard to definitely say what pattern North Korea's number broadcasts has or what its intent is," Yonhap cited Lee Eugene, vice spokesperson at Seoul's unification ministry, as saying.

Since June 2016, North Korea has reportedly broadcast such secretive messages on 36 different occasions, 16 of which were broadcast this year.