South Korea is set to expand its air defence zone to partially overlap China's recently enlarged airspace, South Korean officials have said.

Seoul's defence ministry said on Sunday that the expansion, which covers an extra 66,480 square kilometres, would include two territorial islands to its south, and a submerged rock also claimed by China.

The move would not infringe on the sovereignty of neighbouring countries, said officials in the South Korean capital, and had been discussed in advance with Washington.

Aviation authorities in South Korea say the air zone expansion is in line with international standards, reported Al Jazeera's Stella Kim from Seoul.

Harry Fawcett and Rob McBride discuss the move

"The South Korean government is confident that this won't lead to any military clashes or become an international diplomatic issue," she said.

"The expansion includes a set of islands at the centre of a territorial argument between Beijing and Tokyo, so there wil be a seven-day grace period before the new zone is enacted."

Air defence identification

The new South Korean air zone in the East China Sea overlaps a similar area, first declared by Japan in 1969, and recently claimed by China.

"This is a very direct response to China's decision to expand," said Al Jazeera's Harry Fawcett in Seoul.

Aircraft intending to fly through the area will now be required to inform aviation authorities of all three nations.

South Korea's air defence identification zone was first declared in 1951 during the Korean War to counter potential air intervention by the Chinese. At the time, the more remote islands and submerged rocks were not carefully considered, say analysts.

The new expansion covers the two islands Marado, which is south of Jeju island, and Hongdo, which is south of Geoje island and is also covered by Japan's air defence zone.

Further south, Seoul's expansion also includes the submerged rock named Ieodo, which is home to a strategically located research station operated by South Korea.

China has also claimed that Ieodo is within its exclusive economic zone.