By Maria Kiselyova and Hyonhee Shin

MOSCOW/SEOUL (Reuters) – Russia’s embassy in Seoul on Wednesday said that Moscow had not apologized for an alleged airspace violation the previous day after South Korea said that a Russian attache had expressed “deep regret” and blamed malfunctioning equipment.

A Russian military aircraft entered airspace near a group of islets claimed by both South Korea and Japan on Tuesday, during a long-range joint air patrol with Chinese jets, according to South Korea and Japan, which both scrambled fighter jets in response.

South Korean warplanes fired flares and hundreds of warning shots near the Russian aircraft, and the incident triggered a round of diplomatic protests by countries in the region.

An unidentified Russian military attache in Seoul told South Korean officials on Tuesday that the plane appeared to have “entered an unplanned area due to a device malfunction”, said Yoon Do-han, South Korea’s presidential press secretary.

“Russia has conveyed its deep regret over the incident and said its defense ministry would immediately launch an investigation and take all necessary steps,” Yoon said.

“The officer said such a situation would have never occurred if it followed the initially planned route.”

Hours later, Russia’s embassy in Seoul said there had been no apology.

“The Russian side did not make an official apology,” the embassy in Seoul said, adding it had noted many inaccuracies in the comments by South Korea, Interfax reported.

The incident comes at a delicate time for a region that has for years been overshadowed by hostility between the United States and North Korea and has recently seen a flare-up in tension between South Korea and Japan.

Russia’s public statements on the issue have not mentioned any technical problems, nor has Russia announced any investigation or acknowledged a violation of South Korean airspace.

Yoon said in a later briefing that after the attache admitted a possible mistake and expressed regret, which was taken as Moscow’s official position, Russia “altered” its account by sending a document stating that it did not violate any airspace.

Russia also accused South Korean fighter jets of threatening the safety of Russian aircraft by interfering with their flight and failing to communicate, Yoon said.

Seoul’s defense ministry said Russia was “distorting the truth” and it had evidence to support its claim.

Russia’s Ministry of Defense did not respond to a request to clarify the conflicting accounts.

“The document says that they might take a responsive measure if similar flights by the South Korean Air Force recur,” Yoon said.

An official at the defense ministry earlier told reporters it believed the intrusion could not have resulted from a system error.

He did not elaborate, but another official told Reuters that the two countries plan to hold working-level talks on Thursday in Seoul to clarify what happened.

While troops and naval ships from Russia and China have taken part in joint war games before, they have not conducted such air patrols in the Asia-Pacific region together, according to Russia’s Ministry of Defense.

China’s defense ministry said on Wednesday that China and Russia did not enter the airspace of any other country during their joint patrols on Tuesday.

South Korea and Japan scrambled fighter jets because both claim sovereignty over the disputed islets called Dokdo in Korea and Takeshima in Japan.

The two U.S. allies are mired in a deepening political and trade dispute, which fanned concerns that it might undercut three-way security cooperation to fend off North Korea’s nuclear threats.

The incident also coincided with the visit of U.S. national security adviser John Bolton to South Korea.

Bolton and his counterpart, Chung Eui-yong, discussed the suspected airspace breach during a meeting on Wednesday and vowed close consultations in case of more such incidents, South Korea’s presidential Blue House said in a statement.

(Reporting by Maria Kiselyova in Moscow and Hyonhee Shin in Seoul; Additional reporting by Joyce Lee and Josh Smith in Seoul, and Andrew Osborn in Moscow; Editing by Robert Birsel and Nick Macfie)