A special United Nations human rights investigator said Tuesday that diplomats from North Korea, in what he described as an abrupt and “interesting turn of events,” were now prepared to invite him to visit their isolated nuclear-armed country for the first time — but only if a growing effort aimed at prosecuting North Korea’s leader and other officials for crimes against humanity was dropped.

The investigator, Marzuki Darusman, made the disclosure at a news conference after he presented his annual report to the General Assembly’s human rights commission. Mr. Darusman, a member of a panel that produced a devastating report on human rights abuses in North Korea early this year, said the offer for a visit, which would be unprecedented, had been made by four North Korean diplomats who had unexpectedly agreed to meet with him on Monday.

North Korea’s mission to the United Nations did not respond to requests for comment on Mr. Darusman’s assertions. North Korean diplomats have denounced the panel’s report as a collection of fabrications and smears and have refused to meet with Mr. Darusman or any other panel member. The report said the North Korean authorities maintained a murderous police state and a system of gulag-like prison camps that incarcerated more than 100,000 people. It recommended that the Security Council refer North Korea to the International Criminal Court for prosecution.

In recent weeks, however, North Korea’s reclusive government, possibly sensing that a General Assembly resolution urging such a referral would probably pass by a strong majority, has adopted counterstrategies to avoid an acute embarrassment. They include the government’s own human rights report, released last month, which asserted improbably that North Korean citizens enjoy unparalleled freedoms. The North has also shown more eagerness to engage with South Korea and Japan, and last week it unexpectedly released one of three imprisoned Americans.