In a rare display of political unity, the Democratic People's Republic of Korea and the Republic of Korea on Thursday both condemned Japanese Prime Minister Shinzo Abe for failing to apologise during a US visit for the wartime use of sex slaves.

Their respective foreign ministries each issued statements criticising Abe for distorting history, with Pyongyang comparing him to "psychopaths" and "hooligans".

In an address to a joint session of the US Congress, Abe expressed his "deep remorse" over Japan's actions towards neighboring Asian nations during World War II.

But he stopped short of a full apology demanded by countries such as China and the ROK, especially over the forced recruitment of so-called "comfort women" to serve Japanese soldiers in military brothels.

"It is very regrettable that Japanese Prime Minister Abe's speech at the US Congress ... lacked a sincere apology," the ROK foreign ministry said.

Historians estimate that around 200,000 Asian women, mainly from the Korean peninsula, were forced to work in Japanese military brothels.

A DPRK foreign ministry spokesman said Abe's failure to offer a proper apology was an "intolerable" insult to the women who had suffered.

He accused Abe of working with right-wing Japanese groups to try to negate Japan's war crimes record and avoid responsibility for abuses.