SEOUL, March 27 (Reuters) - North Korea fired two short-range ballistic missiles into the sea off its east coast on Monday morning, South Korea's military said, the latest in a series of launches as a U.S. aircraft carrier is set to arrive in South Korea.

The missiles were fired from North Hwanghae province at 7:47 a.m. (2247 GMT on Sunday) and flew about 370 kilometres (230 miles), South Korea's Joint Chiefs of Staff (JCS) said.

Both missiles appear to have landed outside Japan's exclusive economic zone, according to the Japanese government.

South Korea's military "strongly condemned" the launches as a grave provocation violating United Nations Security Council resolutions, and called for an immediate halt.

"We will keep a close eye on North Korea's various activities and maintain firm readiness posture based on the capability to overwhelmingly respond to any provocations," the JCS said in a statement, adding that it would continue military drills with the U.S. as planned.

The Japanese government also lodged a "strong protest" with North Korea, saying its missile launches threaten the safety and peace of Japan, the region and the international community.

Monday's launches came as the U.S. aircraft carrier USS Nimitz and ships from its accompanying strike group are scheduled to dock at a South Korean naval base in the southeastern port city of Busan on Tuesday.