South Korean air force jets fired 360 rounds of warning shots after a Russian military plane briefly violated South Korea’s airspace twice, Seoul officials have said.

Three Russian military planes – two Tu-95 bombers and one A-50 airborne early warning and control aircraft – initially entered South Korea’s air defence identification zone off its east coast before the A-50 intruded in South Korean airspace, the South’s Defence Ministry said.

South Korean fighter jets then scrambled to the area, including F-16s, and fired 10 flares and 80 rounds from machine guns as warning shots, a ministry official said.

The Russian reconnaissance aircraft left the area three minutes later, but it returned and violated the South Korean airspace again for four additional minutes later on Tuesday, the ministry official said.

Russian Tu-95 strategic bombers
Russian Tu-95 strategic bombers (Pavel Golovkin/AP)

He said the South Korean fighter jets fired 10 flares and 280 rounds from machine guns as warning shots again.

Japanese chief cabinet secretary Yoshihide Suga told reporters later that the firing of warning shots was “absolutely unacceptable” in light of Japan’s territorial claims to Korean-controlled islands that Japan calls Takeshima and South Korea calls Dokdo.

He said Tokyo “strictly objected to Russia and South Korea via separate diplomatic channels and strongly requested the prevention of a recurrence”.

Russia’s defence ministry said in a statement that South Korean fighter jets did not fire any warning shots, though it said they flew near the Russian planes in what it called “unprofessional manoeuvres” and posed a threat.

“If the Russian pilots felt there was a security threat, they would have responded,” the statement said.

It was the first time a foreign military plane has violated South Korean airspace since the end of the 1950-53 Korean War, according to South Korean officials.

The former Soviet Union supported North Korea and provided the country with weapons during the Korean War, which killed millions.

In 1983, a Soviet air force fighter jet fired an air-to-air missile at a South Korean passenger plane that strayed into Soviet territory, killing all 269 people on board.

Relations between Seoul and Moscow gradually improved and they established diplomatic ties in 1990, a year before the break-up of the Soviet Union.

Later on Tuesday, South Korea’s Foreign Ministry and the Joint Chiefs of Staff summoned Russia’s acting ambassador and its defence attache respectively to file a formal complaint with them.

South Korea’s presidential national security adviser Chung Eui-yong told top Russia security official Nikolai Patrushev that South Korea takes Russia’s airspace violation “very seriously” and will take “much stronger” measures if a similar incident occurs, according to South Korea’s presidential office.

The airspace the Russian warplane violated was above a group of South Korean-held islets roughly halfway between South Korea and Japan that has been a source of territorial disputes between them.

A South Korean coast guard looks at Dokdo islets, known as Takeshima in Japanese, through a telescope on the patrol ship Sambong-ho on the East Sea, South Korea
Photo from 2005 showing a South Korean coast guard looking at Dokdo islets, known as Takeshima in Japanese (Ahn Young-joon/AP)

Russia is not a party in those disputes.

The three Russian planes had entered the South Korean air defence identification zone with two Chinese bombers.

But it was not immediately known whether the two countries deliberately did so, according to the South Korean official.

Before their joint flights with the Russian planes, the Chinese warplanes entered South Korea’s air defence identification zone off its south west coast earlier on Tuesday, according to the South Korean official.

Chinese planes have occasionally entered South Korea’s air defence identification zone in recent years.

South Korea’s Foreign Ministry and Joint Chiefs of Staff registered their official protests with Beijing when they summoned China’s ambassador and defence attache respectively.