This year's anniversary comes as the North blew up the liaison office building in June last year in anger over the sending of anti-Pyongyang leaflets by activists in the South.
The North also remains unresponsive to calls from South Korea via liaison and military hotlines after they were restored late July following a yearlong severance.
"The government considers it unfortunate that the operations of the inter-Korean liaison office continue to remain suspended," a ministry official said.
"We will continue to make efforts for the restoration of the inter-Korean communication lines and the resumption of the liaison office," she said.
The official added that the North has not responded to the regular phone calls via the inter-Korean liaison office as of Tuesday morning.
The joint liaison office opened in the North's border city of Kaesong in September 2018 to support inter-Korean exchanges and cooperation after a summit agreement between South Korean President Moon Jae-in and North Korean leader Kim Jong-un in April that year. (Yonhap)