North Korea may be carefully watching who will succeed Shinzo Abe after the Japanese prime minister, who had made resolving the abduction issue a major goal in his political career, expressed his intention to step down on Friday, diplomats said.

"North Korea might be happy to hear that Abe will resign as he has taken a tough posture" against Pyongyang since he became prime minister in December 2012 following his first one-year stint in the post between 2006 and 2007, one of the diplomats said.

Abe, who this week became Japan's longest-serving prime minister in terms of consecutive days in office, has called tackling the issue of Japanese nationals abducted by North Korea in the 1970s and 1980s his "life's work."