Media playback is unsupported on your device Media caption N Korean media cited 'personal discomfort' as grounds for Mr Kim's absence

The North Korean government has said that the country's leader, Kim Jong-un, is healthy.

"No doubt about it," the country's ambassador to the UK told the BBC, despite the leader's non-appearance in public since 3 September.

Ambassador Hyon Hak Bong also said US missionary Kenneth Bae was being held in a "reform institution", which was not the same as a labour camp.

Mr Bae was sentenced to 15 years' hard labour in 2013.

The ambassador said in an email to the BBC: "We have reform institutions where offenders sentenced to penalty of reform through labour by the relevant laws are held and educated through labour. Some Western media interpret them as 'labour camps', but they are reform institutions."

"If I take an example, the place where American citizen Bae Jun Ho (Kenneth Bae) is being held is a reform institution."

A month ago, under the supervision of North Korean officials, Mr Bae gave an interview to Western media where he said he was being treated "as humanely as possible".

His family said, though, that he had previously sent letters saying his health was failing and that he suffered from diabetes.

"No improvement"

The ambassador to London seems to be part of a drive by North Korean diplomats around the world to counter criticism of the country's human rights record.

The United Nations accused North Korea earlier this year of crimes against humanity, including systematic extermination, torture, rape, forced abortions and starvation.

There are moves to indict the country's leader before the International Criminal Court.

The ambassador said the allegations were false and driven by the United States which wanted to topple the regime in Pyongyang.

"Let me make it clear", he said. "We do not have political prisons or political camps."

Human Rights Watch said earlier this year: "There has been no discernible improvement in human rights in the Democratic People's Republic of Korea (DPRK or North Korea) since Kim Jong-un assumed power after his father's death in 2011. The government continues to impose totalitarian rule."

It's hard to know if the ambassador's lengthy communication on the situation in his country is driven by immediate concerns such as any upcoming condemnation at the United Nations, or is a sign of a genuine change of policy.

North Korean diplomats have approached the European Union and said they are prepared to discuss human rights in North Korea.

Whatever is happening in Pyongyang, there is unlikely to be any great change from the West, though, while North Korea pursues nuclear weapons and the missiles to deliver them.

The ambassador said: "Under the present circumstances, there will be no alternative for us but to further strengthen the DPRK's self-defensive deterrence to protect its system and sovereignty."