The top U.S. envoy for North Korea is urging it to pardon imprisoned American Kenneth Bae.

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

Bae was arrested in November 2012 while leading a tour group and sentenced to 15 years of hard labor. He was moved to a hospital last summer in poor health.

Davies said the U.S. government had made direct appeals to North Korean representatives on Bae's behalf.

Davies is 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.