International monitors must be allowed into North Korea in the wake of new claims of human rights abuses, says a British foreign office minister.
The latest defections have caused new concern
Bill Rammell was speaking after a North Korean defector told BBC2's Newsnight he had tested out lethal chemical weapons on political prisoners.
Mr Rammell said he would discuss the "very, very serious" claims during a trip to China this week.
But he said it was right to continue diplomacy with North Korea.
The North Korean defector, a scientist identified only as Dr Kim, said he made notes on how long it took political prisoners to die from the experimental chemical weapons.
"We wanted to determine how much gas was necessary to annihilate the whole city of Seoul," he said.
Lord Butler's report on British intelligence about weapons of mass destruction this month said North Korea probably had enough plutonium to make at least one nuclear weapon.
And it was thought to be developing missiles capable of delivering nuclear weapons as far away as the United States and Europe, said the report.
It added: "North Korea is a particular cause for concern because of its willingness to sell ballistic missiles to anyone prepared to pay in hard currency."
Mr Rammell defended the decision to wage war on Iraq but not on North Korea.
"We tried the diplomatic, peaceful route with Iraq for over 12 years, exactly
the kind of approach we are operating in North Korea now," he told Newsnight.
The Foreign Office minister said talks with North Korea had included concerns about human rights abuses.
"We have persistently said to the North Korean government that they need to
respond on this and that we have very serious concerns," he said.
"At the moment they deny these abuses are taking place. That is why we have said they should allow independent international monitors to go in and verify
exactly what is happening."
Dr Kim's testimony comes as hundreds of defectors arrived in South Korea from the hunger stricken Communist North.
Mr Rammell said he was concerned about the news of the largest single batch of defectors from the hunger-stricken Communist North.
It was an indication
of the plight of the North Korean people, which he would raise both in Beijing and with the North Korean Government, he said.