Sanctions imposed on North Korea are hampering health and science and should be eased, a group of three Nobel laureates have said.
They were speaking in Beijing after visiting Pyongyang in what was billed as an attempt to promote dialogue.
“You cannot turn penicillin into a nuclear bomb,” one of them said.
International sanctions on North Korea were further tightened this year after it claimed to have tested a hydrogen bomb and launched a missile into space.
The laureates’ visit came as a rare party congress opened in North Korea, with leader Kim Jong-un hailing his country’s “great success” in its nuclear advancements.
The event is widely seen as a chance for Mr Kim to cement his power, and South Korea urged the foreign delegation not to visit, fearing it would become a propaganda coup for the North.
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“We didn’t come to criticise them,” said Aaron Ciechanover, who won a Nobel Prize for Chemistry in 2004.
“We really came to converse and to exchange dialogue with students.”
On sanctions, he said “you cannot turn penicillin into a nuclear bomb… You don’t pressurise via making people sicker”.
Foreign visits to North Korea are carefully monitored and public access to information such as the internet strictly limited.
Nobel laureate for medicine Sir Richard Roberts said he was “quite impressed” with what North Korean scientists had achieved despite sanctions.
“This embargo is really hurting the scientists and that’s a great shame,” he said.
The visit was organised by the Vienna-based International Peace Foundation (IPF) and also included Nobel laureate for economics Prof Finn Kydland, Prince Alfred of Liechtenstein and IPF chairman Uwe Morawetz.
The latest sanctions, approved by the UN in March, included export bans on materials used in nuclear and military production as well as restrictions on luxury goods and banking.
A resolution stressed the new sanctions were not intended to have “adverse humanitarian consequences” for civilians, many of whom face financial hardships and shortages of food.