Kim Jong-un has appeared in public for the first time in 20 days, North Korean state media says.

KCNA news agency reports that the North Korean leader cut the ribbon at the opening of a fertiliser factory.

It adds that people at the factory "broke into thunderous cheers of hurrah" when he appeared.

The reported appearance - his first since an event on state media on 12 April - comes amid global speculation over his health.

The latest reports from North Korean media could not be independently confirmed and no pictures were provided.

Asked about Mr Kim's reported reappearance, US President Donald Trump told reporters that he didn't want to comment yet.

What does the state media report say?

According to Korean Central News Agency (KCNA), Mr Kim was accompanied by several senior North Korean officials, including his sister Kim Yo Jong.

The North Korean leader cut a ribbon at a ceremony at the plant, in a region north of Pyongyang, and people who were attending the event "burst into thunderous cheers of 'hurrah!' for the Supreme Leader who is commanding the all-people general march for accomplishing the great cause of prosperity", KCNA says.

Mr Kim said he was satisfied with the factory's production system, and praised it for contributing to the progress of the country's chemical industry and food production, the state news agency adds.

However, the agency provided no photographs of the event.

What started speculation about his health?

Speculation about Mr Kim's health began after he missed the birth anniversary celebrations of his grandfather, state founder Kim Il Sung on 15 April.

The anniversary is one of the biggest events in the North Korean calendar, and Mr Kim usually marks it by visiting the mausoleum where his grandfather lies. Mr Kim had never missed this event.

Claims about Mr Kim's ill-health then surfaced in a report for a website run by North Korean defectors.

An anonymous source told the Daily NK that they understood he had been struggling with cardiovascular problems since last August "but it worsened after repeated visits to Mount Paektu".

This led to a chain of reporting by international media on a single-sourced story.

News agencies then began to run with that claim, and it was all they had until some reports emerged that intelligence agencies in South Korea and the US were monitoring the claim.

But then came a more sensational headline in US media that the North Korean leader was in a critical condition after heart surgery.

US Secretary of State Mike Pompeo appeared to stoke the rumours on 29 April, by saying US officials "hadn't seen" Mr Kim recently.

However, a statement from the South Korean government, and sources at Chinese intelligence - speaking to the Reuters news agency - said this was not true.