North Korea has fired a missile that flew over northern Japan before crashing into the sea.

No effort was made by the Japanese to shoot down the missile, which was launched early in the morning local time, triggering safety warnings.

Japanese Prime Minister Shinzo Abe called the missile an "unprecedented" threat.

There has a been a wave of North Korean missile tests recently but firing projectiles over Japan is rare.

On Friday and Saturday North Korea fired three short-range missiles into the sea off its eastern coast.

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As this latest missile flew towards Japan warning alarms went off across northern Japan, but public broadcaster NHK said there was no sign of any damage.

Mr Abe called the launch an "outrageous act" and an "unprecedented, serious and grave threat [that] greatly damages regional peace and security".

He said his government was doing its utmost to protect people's lives.

Given the missile's flight path the test is being seen as an escalation of tensions on the Korean peninsula.

The South Korean military says that the missile was fired eastward from near the north's capital Pyongyang early on Tuesday.

It passed through the sky over Japan and fell into the North Pacific Ocean, it said, covering a distance of more than 2,700km (1,678 miles) at a maximum altitude of around 550km (342 miles).

The missile flew over the northern Japanese island of Hokkaido before breaking into three pieces and falling into the water, according to local media.

In other reaction:

• A meeting of South Korea's National Security Council (NSC) was convened to discuss the issue, Yonhap reported.
• British Foreign Secretary Boris Johnson expressed "outrage" at North Korea's "reckless provocation"
• The Pentagon said that Tuesday's test did not represent a threat to the US and the military was now working to gather more intelligence about it.

On the two occasions North Korea has fired rockets over Japan in the past - once in 1998 and again in 2009 - the North claimed they were for satellite launches, not weapons.

Earlier this month North Korea threatened to fire missiles towards the US Pacific territory of Guam, while US President Donald Trump warned Pyongyang would face "fire and fury" if it threatened the US.

The US and South Korea are currently engaged in joint military exercises and the North's missile tests are often in response to them.

Thousands of troops from both countries are participating in the drills, which are mainly computer-simulated exercises.