North Korea's ruling Workers' Party has convened a key meeting to discuss important policy issues amid concerns the country may soon conduct a nuclear test.

Attention is focused on whether leader Kim Jong Un will address Pyongyang's nuclear and missile development and relations with the United States and other countries.

State-run Korean Central Television on Thursday reported that the plenary meeting of the party's Central Committee began the previous day, with Kim attending.

It did not report the details of what was discussed. It said the meeting began "amid high political enthusiasm of all the participants who are fully aware of their important duty in the historic struggle for prosperity and development of our great country and the people's wellbeing."

The second day of the meeting is expected to be held on Thursday.

At the plenary meeting held in April 2018 ahead of the first US-North Korea summit, officials decided to halt nuclear testing and test-firings of intercontinental ballistic missiles.

They also decided to close the Punggye-ri nuclear test site in the country's northeast.

But the party's politburo meeting in January suggested it would review the decision. From the following month, the country has test-fired a series of ICBM-class missiles.

The US and other countries are warning that North Korea could soon conduct its seventh nuclear test.