US lawmakers have moved to toughen sanctions against North Korea by targeting money laundering and human rights violations, voicing impatience with the hardline regime.

The House Foreign Affairs Committee on Thursday approved the bill, hours after Japan, a US ally that has usually championed a hard line on North Korea, unexpectedly eased sanctions after rare talks between the arch-enemies.

The House bill would create a blacklist of officials judged to be involved in human rights abuses after a damning report by a UN commission likened abuses by Kim Jong-Un's regime to those under Nazi Germany.

While the United States already maintains sweeping sanctions against North Korea, the proposed law would seek to make the totalitarian state radioactive for banks from third countries, by asking the Treasury Department to consider designating Pyongyang a money-laundering concern.

The move is inspired by the freezing of $US25 million ($A27 million) in North Korean funds in 2005 on US money-laundering and counterfeiting charges at the Banco Delta Asia in the Chinese territory of Macau.

Hard-up Pyongyang responded furiously, refusing to comply with a denuclearisation deal until it received the funds.

The sanctions bill would also reimpose strict restrictions on export licenses that were loosened in 2008 when then-president George W. Bush controversially took North Korea off a list of state sponsors of terrorism as he searched for an elusive final denuclearisation agreement.

"It has been six years since North Korea walked away from the negotiating table. The only thing that has changed since 2008 is that North Korea is closer to miniaturising a nuclear warhead," said Representative Ed Royce, the chairman of the House committee.

"Our North Korea policy, frankly, has been a bipartisan failure," said Royce, a member of Bush's Republican Party.

Representative Tulsi Gabbard, a member of President Barack Obama's Democratic Party, said that North Korea's growing missile program posed a direct threat to her state of Hawaii.

"Strategic patience -- the time for that has come and gone," Gabbard said, referring to the stated policy at the start of the Obama administration of waiting for North Korea to come forward before any changes to US policy.

The vote came after Japanese Prime Minister Shinzo Abe, long known for his hawkish stance on North Korea, announced an easing of several sanctions, including travel restrictions, after North Korea pledged during talks in Sweden to reinvestigate the cases of Japanese civilians kidnapped by the regime's spies in the 1970s and 1980s.

A report earlier this year by the non-partisan Congressional Research Service said that the sanctions bill could put the United States at odds with another ally, South Korean President Park Geun-Hye, if she sought a new push to reconcile with the North.