SEOUL - North Korea fired three ballistic missiles toward the sea off its east coast on Thursday, South Korea said, in the latest such move by the isolated country racing to advance its weapons programmes on the day it first reported a COVID-19 outbreak.

Japan's coastguard also confirmed the launch of a ballistic missile by North Korea, citing its military. The projectile appeared to fall outside Japan's exclusive economic zone, public broadcaster NHK said.

South Korea's Joint Chiefs of Staff said three short-range ballistic missiles were fired from the Sunan area of the North's capital, Pyongyang, where an international airport is located and where the North had said it fired its largest intercontinental ballistic missile (ICBM), the Hwasong-17, on March 24.

The firing was the first after the inauguration of conservative South Korean President Yoon Suk-yeol this week, who has signalled a hard line against the North's weapons development.

Yoon's office said it immediately convened a meeting of its national security council.

The launch, the North's 16th known weapons test this year, also came hours after it reported its first coronavirus outbreak, declaring "gravest national emergency" and ordering a national lockdown.

In its last weapons test on Saturday, the North used a submarine-launched ballistic missile, which it has been aggressively developing in recent years.

North Korean leader Kim Jong Un vowed late last month to expedite the country's buildup of nuclear arsenal, amid stalled denuclearisation talks with the United States.

U.S. and South Korean officials have said Pyongyang's first nuclear test since 2017 could take place as early as this month.

(Reporting by Hyonhee Shin; Editing by Raissa Kasolowsky and Alison Williams)