North Korea says it conducted two missile tests on Friday, marking the fourth day of missile launches by Pyongyang in just over a week.

The state-run Korean Central News Agency on Saturday reported the country's Missile Administration had carried out what it called a "cruise missile super-large warhead power test" and a "new-type anti-aircraft missile test-fire." The test launches took place into the Yellow Sea, which is on the west side of the Korean Peninsula.

These tests were North Korea's fourth missile launch since January 24. The tests have focused on tactical nuclear warhead capable missiles that can fly a long distance at low altitude.

Photos released by the agency show a white-painted round-head missile ascending and then striking a structure on the coast.

The missile appears different from North Korea's conventional cruise missiles, possibly related to development of a new or modified model.

The news agency said the tests are part of the Missile Administration's activities for the rapid development of technologies for new-type weapon systems.

Experts say the weapons are designed to attack the South Korean military, US forces in South Korea and US military bases in Japan. They say the North is likely to continue to test-fire missiles to further develop technologies.