The United Nations Security Council is holding an emergency meeting and is expected to strongly condemn North Korea over its latest missile launches — and possibly press even more sanctions.

South Korean and Japanese officials said a medium-range ballistic missile fired on Wednesday flew about 1,000km and landed near Japan’s territorial waters, one of the longest flights by a North Korean missile.

A second missile was fired immediately after the initial launch but appeared to explode on take-off, the US military reported.

Britain’s deputy UN ambassador Peter Wilson said the test-fire marked the first time a missile landed in Japan’s exclusive economic zone, some 250km from Japan’s northern coast.

“Our objective in this meeting is to draw attention to that fact, but also to come together to very, very clearly condemn it,” Wilson said as he headed into an emergency council meeting called by the United States, Japan and South Korea.

UN Secretary-General Ban Ki-moon said he was “deeply troubled” by the latest test launch, according to his spokesman, saying that “such actions seriously undermine regional peace and stability”.

“We reiterate the call on the DPRK [Democratic People’s Republic of Korea] to heed the united call of the international community to reverse its course and return to the process of sincere dialogue,” said UN spokesman Stephane Dujarric.

North Korea launched a ballistic missile, believed to be Rodong, into the Sea of Japan that fell in waters within Japan’s exclusive economic zone. Photo: AAP

Japan’s UN Ambassador Koro Bessho said he wants to make it clear to the council that “shooting a missile at us — it fell short, but it is a major threat to our national security”.

The Security Council was being briefed behind closed doors by Assistant Secretary-General for Political Affairs Taye-Brook Zerihoun.

In March, the council adopted its fifth and most severe sanctions resolution against North Korea in response to a January 6 nuclear test and a February 7 satellite launch.

The two ballistic missile launches on Wednesday were the third since the United States and South Korea announced plans on July 8 to deploy an advanced missile defence system in South Korea by the end of next year – a move Pyongyang has denounced.

The council has condemned six other launches in April, May and June.

The Security Council has not responded to a July 9 failed attempt by a North Korean submarine to launch a ballistic missile and the July 19 launch of two short-range Scud missiles and a Rodong intermediate-range missile.

UN diplomats, speaking on condition of anonymity because discussions have been private, said attempts to condemn the launches have been held up by China.