South Korean officials say Russia has expressed "deep regret" over the intrusion of one of its military aircraft into South Korean airspace, a claim that Moscow is denying.
Moscow has told South Korea a technical problem was likely to blame for the incident, the office of South Korean President Moon Jae-in was quoted as saying by the Yonhap news agency on July 24.
"Russia said its Defense Ministry will immediately launch a probe and take necessary steps," spokesman Yoon Do-han told reporters. Yoon added that the message had been delivered by a Russian military attache on July 23.
"Moscow said if the aircraft flew according to an initially planned route, this incident would not have occurred," Yoon said.
Separately, Yoon Sang-hyun, chairman of the South Korean parliament's Foreign Affairs Committee, quoted Russia's acting Ambassador Maksim Volkov as telling him that Russia regrets the incident.
Yoon cited Volkov as saying Russia thinks a probe is necessary.
However, Russia's embassy in Seoul immediately denied that Moscow had formally apologized to South Korea over the incident.
"The Russian side did not make an official apology," the embassy said, adding it had noted many inaccuracies in the comments by South Korea, the Russian news agency Interfax reported.
On July 23, Russia's Defense Ministry denied the incident, saying its plane was taking part in the first-ever joint air patrol by Russian and Chinese warplanes over the Sea of Japan and the East China Sea.
The alleged incursion happened over the disputed Dokdo/Takeshima islands, which are occupied by South Korea but also claimed by Japan, which has also protested over the incident.
China's Defense Ministry on July 24 denied any of the planes had entered the territorial airspace of any country.