Seoul: North Korea has built a new greenhouse farm at the air base, which was used to test missiles until last year.

North Korean leader Kim Jong Un attended the opening ceremony, state media said on Tuesday.

The launch on Monday of the Ryonpho Greenhouse Farm, located in the eastern county of Hamju, was to mark the anniversary of the founding of the ruling Workers' Party, a major holiday in North Korea.

The farm has more than 850 blocks of modern greenhouses covering 280 hectares, to be harmonized with some 1,000 houses, schools and cultural and service facilities, the official KCNA news agency said.

Kim's attendance comes after South Korea launched nuclear weapons designed to counter recent joint naval exercises by South Korean and US forces over the past two weeks.

The North's ruling party unveiled the project to transform the Ryonpho air base into a "highly automated farm" and a model for rural civilization, calling it a "top priority task" to help achieve its goal of improving people's lives set at its key policy meeting last December.

The isolated country had used the area for several launches of short-range ballistic missiles, including the KN-25s in November 2019 and the suspected KN-23s in March 2021.

Kim has spearheaded the farm initiative to boost vegetable supplies and praised soldiers and workers for completing the construction in just a few months, KCNA said.

The party plans to "more dynamically and confidently push forward the overall rural development of the country with the Ryonpho Greenhouse Farm as a model," Kim was quoted as saying at the ceremony.

He called for building more large farms, increasing the variety of vegetables to be supplied and ensuring scientific, industrialized production and management at those farms.

North Korea first introduced the similar but slightly smaller Jungphyong Greenhouse Farm in the northeast county of Kyongsong in late 2019 as it pushed for self-reliance amid tightening international sanctions over its nuclear and missile programs.