South Korea's air force shot down an unidentified balloon in late March after the object—thought to have originated in China—crossed the country's de facto maritime border with the North, according to multiple local media accounts.

The incident, first reported by South Korean broadcaster SBS on Thursday, happened in the weeks leading up to the country's mid-April general election, prior to which officials in Seoul had warned of possible interference by Pyongyang.

Inter-Korean relations remain frosty amid North Korean leader Kim Jong Un's frequent missile tests and his regime's promise to launch more spy satellites into orbit this year.

North Korea has yet to comment on the incident. Its embassy in Beijing did not respond to a written request for comment.

China's Foreign Ministry, which is currently observing the country's Labor Day holiday, did not immediately respond to a request for comment.

The flying object, described as a balloon carrying a payload measuring up to 6 feet in length, was detected by air defense radars operated by South Korea's marines on the island of Baengnyeong in the Yellow Sea, known in both Koreas as the West Sea.

According to SBS, the balloon ignored warning shots and was later shot down with machine gun fire by a KA-1 turboprop aircraft, which had been sent to intercept it as it crossed the Northern Limit Line, the de facto inter-Korean maritime boundary disputed by Pyongyang.

South Korean navy boats sent to the site of the shootdown were unable to recover any of the debris, reports said. The Yonhap news agency said on Friday that the unidentified object was without a power source.

SBS said Seoul's military assessed the balloon had originated from China and likely drifted through North Korea.

A separate report by South Korean TV station JTBC, which cited South Korea's Joint Chiefs of Staff, said the object may have been privately owned and used for advertising, although its source could not be confirmed.

South Korea's Foreign Ministry could not be reached for comment.

The United States shot down what it said was a Chinese spy balloon carrying sophisticated equipment in February last year after it spent days drifting across America.

The Chinese government said it was a meteorological device that had been blown off course by seasonal winds.

For several months, Taiwan says it has been tracking balloons launched from the Chinese mainland, some of which have entered its territorial airspace and overflown its main island.

Taipei believes the balloons are weather-monitoring devices, but said the intensity of the activity was a form of harassment. Beijing, which claims Taiwan as part of its territory, said weather balloons were "nothing new."

Taiwan's Defense Ministry first disclosed the locations of Chinese balloons late last year. From December 7 to February 17, it reported at least 107 of the objects, which surged in number around the time of Taiwan's presidential election in mid-January.

Since then, however, only 14 balloons have been reported around Taiwan's airspace, with the last appearing on April 10, according to Newsweek's analysis of publicly available data.