The Head of the North’s Atomic Energy Institute (AEI) said that North Korea has resumed normal operations at the Yongbyon complex, the country’s main nuclear facility.

The confirmation on Tuesday, came a day after suggestions by the Chief of the National Space Agency of a possible satellite rocket launch next month.

The nuclear reactor is seen as its main source of weapons-grade plutonium and the move raised the second red flag in 24 hours over its nuclear and ballistic missile programs.

Analysts said the two statements were clearly coordinated and partially aimed at raising tensions to place North Korea firmly on the agenda of an expected US-China summit later this month.

The announcement about Yongbyon is the first official confirmation from North Korea that it has restarted operations there.

Pyongyang claimed it had made a device small enough to fit a nuclear warhead on to a missile, which it could launch at its enemies.

However, US officials had cast doubt on this claim and experts said it is difficult to assess the progress North Korea had made on miniaturisation.

Two big claims had been made as the country prepares for the 70th anniversary of the foundation of the ruling Workers Party. It said the nuclear facility producing material for bombs was fully operational.

Pyongyang has indicated it would launch a rocket soon to carry a satellite into space but the US and South Korea believe it would be a test of a long-range military missile.

Most reliable observers think North Korea already has nuclear material for 12 atomic bombs, but may not be able to make those bombs small enough to go on a rocket.

North Korea said on Tuesday in state media that the plutonium and highly enriched uranium facilities at its main Yongbyon nuclear complex had been “rearranged, changed or readjusted and they started normal operation,” and that its scientists had improved “the levels of nuclear weapons with various missions in quality and quantity.”

A day earlier, the North’s Aerospace Agency said it was ready to launch new satellites aboard long-range rockets as part of celebrations of next month’s ruling communist party anniversary.

Yongbyon’s reactor was shut down in 2007 but Pyongyang vowed to restart it in 2013, following its third nuclear test and amid high regional tensions.