The United States, Japan and South Korea have imposed fresh sanctions on North Korean individuals and entities in response to Pyongyang's recent missile tests.

Washington's action blocks any assets of three North Korean officials in the US, and is a largely symbolic step against an isolated country that has defied international pressure over its weapons programmes.

The US Treasury Department also threatened sanctions against anyone who conducts transactions with Jon Il Ho, Yu Jin and Kim Su Gil, who were identified as directly involved in weapons development.

The recent North Korean missile launches, including the test of an intercontinental ballistic missile with the range to hit the US mainland, "pose grave security risks to the region and entire world," Secretary of State Antony Blinken said in a statement.

The sanctions "underscore our sustained resolve to promote accountability in response to Pyongyang's pace, scale and scope of ballistic missile launches".

Mr Blinken added that the action was taken in coordination with US allies South Korea and Japan, and noted that the European Union issued similar designations of the three in April.

Tokyo and Seoul have also announced new sanctions today.

South Korea said it would target eight individuals, including a Taiwanese and a Singaporean national.

They have "contributed to North Korea's nuclear and missile development and evasion of (pre-existing) sanctions", the South Korean foreign ministry said in a statement.

All are already subject to US sanctions, the ministry added, and South Korea's new restrictions are expected to "alert the domestic and international community of the risks of transactions with these entities".

Japan said that in response to Pyongyang's "provocative acts", it was freezing the assets of three North Korean groups: Korea Haegumgang Trading Corp, Korea Namgang Trading Corp and Lazarus Group, and one person, Kim Su Il.

The US has voiced frustration that China, North Korea's closest ally, and Russia have blocked efforts at the UN Security Council to impose tougher sanctions.