North Korea has rejected planned shipments of AstraZeneca's Covid-19 vaccine that were being organised under the global COVAX distribution scheme due to concerns over side effects, Reuters quoted a South Korean think-tank as saying on Friday.

COVAX has said it would provide nearly 2 million doses of AstraZeneca's shots to North Korea. The first batch had been expected in late May but was delayed amid protracted consultations, South Korea said last month.

North Korea has not reported any Covid-19 cases, a position questioned by South Korean and US officials. The reclusive country has, however, imposed strict anti-virus measures, including border closures and domestic travel curbs.

According to the report by the Institute for National Security Strategy (INSS), which is affiliated with South Korea's spy agency, Pyongyang is now looking at other vaccine options.