Former Foreign Office minister Bill Rammell is the only British minister to have visited North Korea.
Speaking to Daybreak he said North Korea was the "strangest place" he had ever been to.
He added: "There is probably a degree of brainwashing, the like of which I have never seen anywhere else in the world before."
Taiwan have become the first country to advise its people to stay away from Korea.
American intelligence officers in South Korea say they have seen enough evidence to expect a missile test "any time now".
Daybreak's Richard Gaisford reports from Seoul.
South Korea has upped its alert level to 'vital threat' after reports that North Korea could carry out a missile test at any time.
It comes on the day President Obama meets with UN Secretary General Ban Ki-Moon to discuss the crisis, Daybreak's Richard Gaisford reports.
Hyeonseo Lee escaped North Korea to the South, speaking to Daybreak's Richard Gaisford she said that most Koreans "don't know the truth".
She added that many people living in North Korea think the actions of their leaders are necessary because of the propaganda they believe.
The border between South and North Korea remains tense on today, as more South Korean workers returned from the Kaesong industrial complex.
Vehicles loaded with goods were seen passing through a checkpoint heading south across the Demilitarised Zone that divides the two nations.
North Korea has pulled out its 53, 000 workers from the Kaesong complex, which is North Korea's last major economic link with the South.
South Korea and the US remain on high alert for a North Korean missile launch, Reuters reports.
North Korea has stationed as many as five medium-range missiles on its east coast, according to defence assessments made by Washington and Seoul, possibly in readiness for a test launch that would demonstrate its ability to hit US bases on Guam.
Today, officials in Seoul said there were no signs that additional steps had been taken today that would indicate the North had moved closer to a launch.
Russian foreign minister Sergei Lavrov has said his country agrees with the stance taken by the United States in regard to North Korea.
But he warned against American-backed military exercises in the region, the Russian news agency interfax has reported.
Foreign Minister Yun Byung-se said his country had asked China and Russia to attempt to persuade the North to soften its hardened stance and abandon any plans for a launch.
Officials in Seoul said surveillance of North Korean activity had been boosted. Missile transporters had been spotted in South Hamgyong province along North Korea's east coast, a rumoured spot for a launch.
"According to intelligence obtained by our side and the US, the possibility of a missile launch by North Korea is very high," Yun told the South Korean parliament.
A large contingent of international marathon runners are expected to be welcomed in North Korea despite the safety warnings to foreign embassy staff in the country.
Competitors from Ukraine, the Czech Republic, Zimbabwe, Kenya and Ethiopia are expected to join 600 North Koreans in Friday's race, the North's state news agency has said.
The annual Mangyongdae Prize International Marathon, now in its 26th year, is recognised by the International Association of Athletics Federations (IAAF).
The race is held as part of celebrations for the birthday of the North's founding hero Kim Il Sung, which falls on Saturday and will be marked by a big military parade.