By Nobuhiro Kubo

TOKYO (Reuters) -North Korea fired two ballistic missiles early on Sunday, Japanese authorities said, in what marked the seventh such launch by Pyongyang in recent days, a series of exercises that has sparked widespread alarm in both Washington and Tokyo.

Both missiles reached an altitude of 100 km (60 miles) and covered a range of 350 km, Japan’s State Minister of Defence, Toshiro Ino, told reporters. The first was fired at around 1:47 a.m. local time (1647 GMT) and the second one some six minutes later.

Both fell outside Japan’s exclusive economic zone and authorities were looking into what kind of missiles were launched, including the possibility that they were submarine-launched ballistic missiles, he said.

On Tuesday, nuclear-armed North Korea test-fired a ballistic missile farther than ever before, sending it soaring over Japan for the first time in five years and prompting a warning for residents there to take cover.

Ino said Tokyo would not tolerate the repeated actions by North Korea. The incident mark the seventh such launch since Sept. 25.

North Korea, which has pursued missile and nuclear tests in defiance of U.N. sanctions, said on Saturday its missile tests were for self-defence against direct U.S. military threats and had not harmed the safety of neighbouring countries and regions.

“Our missile tests are a normal, planned self-defence measure to protect our country’s security and regional peace from direct U.S. military threats,” said state media KCNA, citing an aviation administration spokesperson.

The United States and South Korea held joint maritime exercises on Friday, a day after Seoul scrambled fighter jets in reaction to an apparent North Korean bombing drill.

The United States also announced new sanctions on Friday in response to North Korea’s latest missile launches.