Seoul The US is working to break an “information blockade” that allows North Korea to hide its rights abuses and keep its people away from news of the wider world, President Barack Obama’s envoy on North Korean human rights said Thursday.

North Korea's media isolation means that its “deplorable human rights conditions” draw far less world attention than abuses in the Soviet Union did several decades ago, Robert King said during a speech at a rights forum in Seoul.

“Breaking the information blockade is the key to positive change in North Korea,” King said. Because Pyongyang succeeds in controlling what's “flowing into, within and out of North Korea”, King said, “in this era of virtually instantaneous global information, North Korea remains the most extreme example of isolation”.

Animosity between the rival Koreas is high following a North Korean rocket launch in April that Washington, Seoul and others condemned as a cover for a test of banned long-range missile technology. Pyongyang, which says the launch was meant to put a satellite into orbit, has regularly accused South Korea's conservative government of trying to “hurt the dignity” of the North since Kim Jong Un took power following the December death of his father, Kim Jong Il. North Korea's military has threatened to attack Seoul and its conservative media if it doesn't receive an apology for perceived insults.

North Korea has virtually no general internet access and severely restricts mobile phone communication, King said, citing a recent information access report conducted for the State Department and based on extensive interviews with North Korean refugees.

The US broadcasts news into North Korea, King said, in an effort to provide independent sources of information about the outside world and to “break down the isolation of the people”.

Radios, which are illegal in North Korea if they can be tuned to non-state controlled stations, are the only “real-time direct source of sensitive outside news available nationwide”, King said.

North Korea responds by trying to jam foreign news broadcasts, including those by US- and South Korean-funded stations, according to Martyn Williams, who writes the blog

Pyongyang denies abusing its citizens’ rights. But defectors say those who oppose the ruling party and state face imprisonment. Amnesty International estimates as many as 200,000 people are being held in North Korean labour camps today, based on satellite imagery and defector accounts. North Korea denies the existence of such gulags.

Hunger in North Korea is also a long-standing worry of outside governments and groups. The United Nations said Tuesday in a detailed update on the humanitarian situation that millions of North Korean children don’t get the food, medicine or health care they need to develop physically or mentally, leaving many stunted and malnourished.

A recent statement from the North's state-run Korean Central News Agency said Washington has the "bad habit of malignantly slandering the independent countries opposed to its high-handed practices" by “politicising human rights”.

“If the US is to truly respect the human rights of the Korean people, it should immediately roll back its hostile policy towards (North Korea) and stop military provocations against it and moves to tighten the sanctions and stifle it,” the KCNA statement said.

King visited North Korea a year ago and said he raised US worries about rights abuses with government officials. He said that US envoys who worked on a now-scrapped deal where North Korea would have got 240,000 metric tonnes of food aid in exchange for a moratorium on nuclear and missile tests also told their North Korean counterparts that North Korea must improve its human rights record to join the international community.