President Moon Jae-in departed Sydney on Wednesday to return home from a four-day state visit to Australia during which the countries agreed to expand cooperation on securing stable supply chains.

Moon began his visit in Canberra on Sunday where he met with Australian Prime Minister Scott Morrison for a summit on deepening ties in defense, pandemic response and strengthening supply chains with the help of resource-rich Australia's critical minerals.

The two leaders also agreed to upgrade the bilateral relationship to a comprehensive strategic partnership on the occasion of the 60th anniversary of formal diplomatic relations this year.

Following the talks, Moon visited a war memorial to pay his respects to the Australian troops who died fighting alongside South Korea during the 1950-53 Korean War and had dinner with Australian veterans of the war.

On the second leg of his trip, the president traveled to Sydney on Tuesday to meet with Australia's opposition leader Anthony Albanese and to discuss supply chain issues with the country's business leaders.

Moon became the first South Korean president to pay a state visit to Australia in 12 years and the first foreign leader to be invited by the country since the start of the pandemic.

"Australia and South Korea will overcome COVID-19, the climate crisis and supply chain insecurities and lead a new change," he wrote on Facebook before taking off from Sydney.

"I extend my deep thanks to Australian Prime Minister Scott Morrison who accompanied me with his family until the last day."

Moon is due to arrive at Seoul Air Base in Seongnam, just outside the capital, late Wednesday. (Yonhap)