Foreign Office minister Bill Rammell has challenged North Korea to answer accusations of widespread human rights abuses after arriving in the country.
Talks continue about North Korea's weapons and human rights record
Embarking on three days of talks, he also urged North Korea to address fears over its nuclear programme and emerge from international isolation.
Mr Rammell is the first British minister ever to visit North Korea.
The UK refused all previous invitations until the communist state agreed to discuss human rights.
North Korea faces accusations of using torture and the death penalty as
well as arbitrary detention, inhumane prison conditions and the near-total
suppression of fundamental freedoms.
Human rights groups say public executions are carried out in front of large
crowds with some prisoners killed in front of their families.
Mr Rammell opened talks on the state's human rights record, describing recent allegations as "the worst in the world".
North Korea's vice foreign minister Kung Sok Ung has promised Mr Rammell another meeting with other officials on Monday.
The highly secretive country is in six-nation talks over its nuclear weapons, but it has threatened to pull out because of perceived American hostility.
While Britain is not involved in the six-nation talks, it is seen as influential because it is a permanent member of the UN Security Council as well as being a key player in the EU and, most importantly, because of its special relationship with the US.
Mr Rammell's visit comes as intense diplomatic efforts are under way to persuade North Korea to give up its nuclear weapons programme.
North and South Korea, the US, Japan, China and Russia are taking part in the negotiations.
Mr Rammell is being accompanied by the Foreign Office's chief human rights expert, Jon Benjamin, who he hopes will make a return visit to Pyongyang at a later date.
"I am certainly realistic about our expectations," Mr Rammell said.
"This is the start of a very, very long haul to try to edge North Korea back from complete isolation."
Mr Rammell will use Libya as an example of a nuclear state that has been welcomed back by the international community.
He will also highlight the advantages that would benefit North Korea if it opened up: international aid and help with energy supplies could follow.
"North Korea has a key choice," he said.
"It can engage in this process and
get rid of what it has got and promise not to develop anything further.
"Then all sorts of positives can come its way. Isolation is the alternative route."
North Korea has claimed to have nuclear weapons and to have been working on developing its arsenal.
But the outside world has been unable to verify those claims due to the secretive nature of the regime.