A U.S. diplomat on Tuesday urged North Korea to pardon imprisoned American Kenneth Bae, saying he is in poor health and needs to return home.

U.S. Special Representative for North Korea Policy Glyn Davies' call for Bae's freedom follows a news conference given by the missionary earlier this month at which he said his situation was growing more difficult.

"We hope that they're willing to release Kenneth Bae," Davies told reporters following talks with Chinese officials in Beijing. "His family is understandably very worried about his fate and would like him to be returned to them."

Bae was arrested in November 2012 while leading a tour group and sentenced to 15 years of hard labor for unspecified anti-government activity. He was moved to a hospital last summer in poor health, but said at his news conference that he was being transferred back to prison.

Davies said the U.S. government had made direct appeals to North Korean representatives on Bae's behalf. While North Korea has released detained Americans before following appeals, it has shown no indication that it is willing to do so in Bae's case.

Bae's supporters say he did no wrong, although he and his family have apologized for any violations of North Korean law. Davies said Bae has already been held longer than any other American in recent decades and, having been tried and convicted, now deserves to be set free.

"North Korea I think has made its point about Kenneth Bae and we are in frequent communication with the North Koreans to try to find a resolution to this issue. It's very, very important to us," Davies said.

Davies was in Beijing for talks on how to persuade North Korea to return to nuclear disarmament talks.

Bae's mother and sister are to meet with U.S. Secretary of State John Kerry on Tuesday in Washington.