SEOUL (Kyodo) -- North Korea blew up parts of inter-Korean roads on its side of the border on Tuesday, according to South Korea's military, destroying what was once a symbol of the two Koreas' cooperation.

"North Korean forces conducted explosions, presumably to block the inter-Korean roads" in Gyeongui and Donghae around noon, South Korea's Joint Chiefs of Staff said.

Later in the day, Seoul's public broadcaster, KBS, reported, citing a senior government official, that North Korean leader Kim Jong Un visited the site to inspect the preparations for blowing up the roads.

Kim arrived at the location in a Lexus, a luxury brand of Japan's Toyota Motor Corp., KBS said. U.N. Security Council resolutions prohibit North Korea from importing luxury goods as part of sanctions imposed in response to its nuclear and ballistic missile tests.

The South Korean military responded by firing warning shots south of the military demarcation line separating the two Koreas, the JCS said, adding that it has strengthened surveillance and readiness in coordination with the United States.

The JCS said North Korea also deployed heavy equipment on its side, apparently to clear debris after the explosions.

South Korea's Unification Ministry expressed deep regret over the explosions, accusing North Korea of repeating "regressive acts."

"This act reflects the same behavior North Korea exhibited four years ago," it said in a statement, referring to the North's blowing up of an inter-Korean liaison office in its border city of Kaesong in June 2020 after being angered by defectors in the South sending propaganda leaflets across the border.

North Korea said Wednesday last week it would cut road and railway links with South Korea and fortify areas on its side of the border amid heightened tensions between the two countries.

It said the danger of war was escalating along the border, calling the step a military measure to completely separate its territory from that of South Korea, according to a report by state-run media.

The road links were part of projects promoting inter-Korean friendship and cooperation, which began following the first-ever North-South summit in 2000.

But the road construction, which had been suspended whenever bilateral relations deteriorated, effectively came to a halt after South Korean President Yoon Suk Yeol, a conservative who signaled a shift toward a more hardline stance on inter-Korean ties, came to power in 2022.

North Korea has also claimed that South Korea had flown the unmanned aircraft into its airspace three times earlier this month. It announced Sunday that it has ordered artillery units along the border to be "fully ready to open fire" in response to any further drone flights.

Kim Yo Jong, the leader's sister, said Tuesday there was "clear evidence" that South Korea's "military gangsters are the main culprit of the hostile provocation" by intruding into the skies over Pyongyang, the country's capital, according to the official Korean Central News Agency.

South Korea has declined to confirm whether its military or a civilian organization sent the drones.