SEOUL: South Korea's President Moon Jae-in pledged on Thursday to upgrade the country's alliance with the United States and prepare a comprehensive North Korea strategy in a phone call with US President Joe Biden, Moon's office said.

The call comes as Moon, who had offered to be a mediator between the United States and North Korea, faces the challenge of getting the stalled talks between Washington and Pyongyang back on track.

The two leaders affirmed the necessity to prepare a comprehensive North Korea strategy aimed at denuclearization of the Korean Peninsula, presidential spokesman Kang Min-seok said.

"President Biden appraised the efforts of South Korea, the key country involved to resolve the issue on the Korean Peninsula,... and said will work closely with the South towards a common goal," Kang said.

The White House said in a statement that Biden stressed his commitment to strengthen US-South Korea alliance and the two countries had agreed to coordinate closely on North Korea.

North Korean leader Kim Jong Un and former US President Donald Trump agreed to work towards the denuclearisation of the Korean peninsula at their first summit in 2018, but a second summit and subsequent working-level talks fell apart.

Moon also welcomed what he described as "America's return" in the midst of mounting global challenges - the COVID-19 pandemic, climate change and economic polarization.

Biden has said a response to climate change will create new jobs, while Moon has introduced his ambitious Green New Deal aimed at economic recovery from the coronavirus fallout.

During a call in November after Biden's election victory, Moon vowed to promote economic relations with the United States by building a carbon neutral economy.

Biden and Moon also agreed on the immediate need for the restoration of demacracy in Myanmar, the White House said, after the country's army seized power on Monday.