North Korea fired what appeared to be several land-to-ship missiles off its east coast on Thursday, South Korea's military said, the latest in a fast-paced series of missile tests defying world pressure to rein in its weapons programme.

The launches come less than a week after the United Nations Security Council passed fresh sanctions on the reclusive state, which said it would continued to pursue its nuclear and missile programme without delay.

It also comes a day after South Korea said it will hold off on installing remaining components of a controversial U.S. anti-missile defence system that has angered North Korea's main ally, China.

The missiles were launched Thursday morning from the North Korean coastal city of Wonsan and flew about 200 km (124 miles), South Korea's Office of Joint Chiefs of Staff said in a statement.

Under third-generation leader Kim Jong Un, North Korea has been conducting missile tests at an unprecedented pace in an effort to develop an intercontinental ballistic missile (ICBM) capable of hitting the mainland United States.

Compared to the different types of ballistic missiles Pyongyang has recently tested, the missiles launched on Thursday are considered to be more defensive in nature, designed to defend against threats such as enemy warships.

North Korea unveiled a number of new weapons at a massive military parade on April 15 to mark the birth anniversary of the state's founding leader and has since tested some of them.

"Looking at North Korea’s pattern of missile launches, it has been revealing what it brought to the recent military parade," said Kim Dong-yub, a military expert at Kyungnam University’s Far Eastern Studies in Seoul. "What appeared to be a new type of land-to-ship missile equipped with four launching canisters was unveiled at the parade. I think this might be what was used today."

THAAD DEFENCE DELAYED

South Korean President Moon Jae-in has been briefed on the latest launch, the military said, declining to give further details.

Thursday's launch is the fourth missile test by North Korea since Moon took office on May 10 pledging to engage in dialogue with Pyongyang, saying sanctions and pressure alone have failed to resolve the growing threat from the North's advancing nuclear and missile programme.

Moon had also promised to review the deployment of the U.S. Terminal High Altitude Area Defense (THAAD) system in South Korea. On Wednesday, his presidential office said installation of four additional launchers would be halted until an assessment of the system's impact on the environment was completed.

The introduction of the THAAD system, which includes a far-reaching radar that China worries could upset the regional security balance, has sparked protests in South Korea and a backlash in China against South Korean business interests.

There was no immediate reaction from China to the latest test.

Seoul and Washington were analysing the launches for further information, South Korean officials said.

Japan is on high alert and will analyse information in cooperation with the United States and South Korea, Kyodo news agency quoted Japanese Foreign Minister Fumio Kishida as saying.

Japan's navy and air force conducted military drills with two U.S. aircraft carriers in the Sea of Japan last week, following similar joint U.S.-South Korea exercises.

"North Korea likely wanted to show off its ability to precisely target a large warship, in relation to the joint military drills involving U.S. aircraft carriers," Roh Jae-cheon, South Korea's Joint Chiefs of Staff spokesman told a media briefing. "By testing different types of missiles, North Korea also appears to be aiming to secure the upper hand in relations with South Korea and the United States."

In the three earlier launches, North Korea tested different kinds of ballistic missiles, two medium-to-long range missiles as well as a short-range Scud class weapon.

The isolated country, which has conducted dozens of missile tests and tested two nuclear bombs since the beginning of 2016 in defiance of U.N. Security Council resolutions, says the programme is necessary to counter U.S. aggression.

U.S. President Donald Trump has been pressing China aggressively to rein in North Korea, warning that all options, including a pre-emptive military strike, are on the table if Pyongyang persists with its nuclear and missile development.