North Korea has insisted that recent embassy closures are simply part of "regular affairs" to improve its external relations, after Seoul said it was a sign of Pyongyang's "dire economic situation".

In the past week, North Korea shut embassies in Angola and Uganda. It also closed its diplomatic missions in Hong Kong and Spain.

South Korea said this week that these moves offered a "glimpse of North Korea's dire economic situation, where it is difficult to maintain even minimal diplomatic relations with traditional allies".

However, a spokesperson of Pyongyang's foreign ministry said the changes were "part of the regular affairs... to promote their national interests in external relations", in comments posted on the ministry's website on Friday.

"In line with the changes in the international environment and the state external policy, we are either closing or newly opening diplomatic missions in other countries," said the official, without specifying which embassies were being opened or closed down.