A flurry of diplomatic efforts between China, the United States and the Democratic People's Republic of Korea have raised hopes for the release of US citizen Kenneth Bae and the resumption of stalled Six-Party Talks.

The US State Department announced on Tuesday that Robert King, special envoy for DPRK human rights issues, will travel to Pyongyang on Friday at the invitation of the government of the DPRK, on a humanitarian mission to secure Bae's release.

Bae was arrested in the DPRK in November 2012 and sentenced in April to 15 years of hard labor for hostile acts against the country.

"King will request the DPRK pardon Mr Bae and grant him special amnesty on humanitarian grounds, so that he can be reunited with his family and seek medical treatment," the statement said.

King's trip will not be directly connected to the nuclear issue, Seoul-based Yonhap News Agency quoted an unnamed official of the Republic of Korea Ministry of Foreign Affairs and Trade as saying on Wednesday.

But the "possibility cannot be ruled out" that the US special envoy will serve as a messenger, bringing information from the DPRK to the White House regarding the situation on the peninsula, said Huang Youfu, a professor of Korean studies at Minzu University of China in Beijing.

"We cannot expect too much from his role as a messenger," Huang said.

While King travels to the DPRK, Danny Russel, US assistant secretary for East Asian and Pacific Affairs, will visit Beijing, Seoul and Tokyo next week to discuss bilateral and regional issues, including the latest situation on the Korean Peninsula, Yonhap said.

It will be Russel's first visit to Northeast Asia since he was officially appointed early this month. Previously, Russel served on the White House National Security Council.

Officials from the US, the ROK and Japan have insisted that Pyongyang show more sincerity by first renouncing its nuclear program before they consider restarting talks.

Scott Snyder, a senior fellow for peninsular studies and director of the Program on US-Korea Policy at the US Council on Foreign Relations, believes Washington is still waiting for Pyongyang to take the necessary steps to create conditions for resuming the Six-Party Talks.

"I do not know if Russel's trip will result in the DPRK taking these steps," he said.

Tensions on the peninsula flared following the DPRK's nuclear test in February - its third.

On Monday, Wu Dawei, China's special envoy for Korean Peninsula affairs, arrived in Pyongyang with hopes of restarting the Six-Party Talks and further improving the situation on the peninsula.

Wu was invited by the DPRK's top nuclear negotiator, Kim Kye-gwan, who visited Beijing in June.

Huang, the Chinese professor, said the frequency of diplomatic interactions and communications among relevant parties to the talks of late resulted from the easing of tensions on the peninsula.

"It is impossible to realize such frequent interactions when tension is running high. With enough updates of information, they are adjusting their policies for greater progress on denuclearizing the peninsula," Huang said.

The professor said the talks are still the best option for achieving a peaceful peninsula, and Beijing is striving hard to resume them.

The talks, begun in 2003 in response to the DPRK's withdrawal from the Nuclear Non-Proliferation Treaty, involve the DPRK, the ROK, China, the US, Japan and Russia. They have been stalled since 2008.

Tensions have eased in the past three months. Seoul and Pyongyang agreed this month to reopen their jointly run Kaesong industrial zone in the DPRK border city.