The head of a U.N. inquiry into human rights in North Korea appealed on Tuesday for access to the country, even as Pyongyang condemned his commission's work as slanderous and provocative.

The three-member Commission of Inquiry chaired by retired Australian judge Michael Kirby has just wrapped up hearing five days of often harrowing testimony in the South Korean capital -- mostly from North Korean defectors.

As he prepared to give a final press conference Tuesday, the North's official Korean Central News Agency (KCNA) launched a bitter attack on the hearings in Seoul, calling the witnesses "human scum" manipulated by the South Korean authorities.

The commentary said the commission's work would only set back recent progress towards engagement between North and South Korea after months of heightened military tensions.

The North, which strongly denies allegations of rights abuses, has refused to recognize the commission and barred it visiting the country.

Despite the KCNA attack, Kirby issued another in a long series of formal and informal appeals to North Korea to grant his three-member panel of experts access.

"We will act with respect, we seek to find facts, we will provide due process, we will have no preconceptions," the retired Australian judge told reporters.

"We are not a prosecutor. We are not a judge. An ounce of evidence is worth many, many pounds of insult or attack.

"The best way for North Korea to respond is with evidence... and by letting us inspect sites where abuses are alleged to have taken place," he said.

The commission has already made repeated requests for access, including a formal written letter to North Korean leader Kim Jong-un, but it has had no direct response.

The Commission of Inquiry is the first United Nations expert panel to officially examine North Korea's human rights record, and plans to collect witness testimony in Japan, Thailand, Britain and the United States.

The final report is due to be submitted to the U.N. Human Rights Council in March next year, and Kirby said he expected the U.N. to act on any recommendations it might make.

"It's difficult to accept that the international community established this commission without the intention that it would lead somewhere," he said.

Much of the testimony gathered from the dozens of witnesses who participated in the public hearings in Seoul has been documented before, by rights groups, NGOs and in books written by the individuals themselves.

Kirby said he had been "greatly affected" by the testimony, but stressed that it did not always amount to evidence of alleged wrongdoing.

He cited allegations of medical experiments on people with mental disabilities as one contention that could not be established.

He also said there was not enough evidence to prove the North Korean state wilfully engaged in policies that deliberately led to starvation during the famine of the mid-1990s.

"But there is of course, a fine line between what is deliberate and what is the result of persistent and wilful incompetence," he said.

He also highlighted "believable, repeated, highly specific" testimony on the "inhumane" conditions in camps for both political and non-political prisoners, as well as the use of extra-judicial executions and torture. (AFP)