North Korea Saturday fired seven ballistic missiles off its eastern coast over a stretch of several hours, violating the U.N. sanctions and sending an apparent message of defiance to the United States which commemorated its Independence Day.

"North Korea fired two missiles toward the East Sea from the Gitdaeryong base near Wonsan, Gangwon Province, between 8:00 a.m. and 8:30 a.m. today. And it fired another one into the East Sea from the same site around 10:45 a.m.," Yonhap reported citing an official at the Joint Chiefs of Staff (JCS).

All the missiles are estimated to have a range of 400-500km, covering the entire South Korea within the target range.

South Korea's foreign ministry lashed out at the reclusive neighbor's ballistic missile launch, calling it a clear violation of U.N. Security Council resolutions that ban the communist nation from any activity related to a ballistic missile program.

"It is a provocative act that clearly violates U.N. Security Council resolutions 1695, 1718, and 1874 that bar North Korea's every activity related to ballistic missiles," the ministry said in a statement.

"The government expresses deep regret over North Korea's continued acts to escalate tensions in Northeast Asia in ignorance of the U.N. Security Council resolutions and urges North Korea to faithfully implement the resolutions," it added.

The launches came two days after North Korea fired four short-range cruise missiles and will likely ramp up the already charged tension in the region as Washington tries to solicit support for strict enforcement of the U.N. sanctions on Pyongyang for its nuclear test in May.

The official said the North shot three more missiles from the same site at around noon, at 2:50 p.m. and at 4:10 p.m., adding the military is analyzing the exact type of the missiles and North Korea's intentions.

The authorities said the missiles are apparently ballistic ones, probably a Scud type, given the trajectory and flight distances. But they did not rule out the possibility that what the North fired might have actually been Rodong missiles, a modification of Scud missiles.

The North is believed to have about 1,000 ballistic missiles alone ― including nearly 700 Scud missiles of various types and 320 Rodong missiles.

Previously, North Korea test-fired a long-range Taepodong-2 missile, along with several short-and mid-range missiles, on U.S. Independence Day in 2006.