South Korea is considering expanding its air defence zone to reinforce its claim to territories in the East China Sea as tensions continue to rise in the region.

Lawmakers and security agencies in Seoul were said to be discussing strategies on how to respond to the creation of an air defence zone by China over a disputed archipelago believed to lie in resource-rich waters.

"Since China's unilateral declaration, we have discussed ways to expand KADIZ (the Korean Air Defence Identification Zone) and related agencies have now formed a general understanding that expansion is necessary," a South Korean official told the state-run Yonhap news agency.

China unilaterally declared an air defence zone above a group of islands called Diaoyu in China and Senkaku in Japan. The move, made after decades of disputing ownership of the archipelago and the seas around it, enraged Japan, South Korea, the US and Australia.

Japan, the US and South Korea have all sent military aircraft through the zone without complying with Beijing's newly installed regulations. The restrictions demand that aircraft in the zone must be identified and a flight plan to submitted to Chinese aviation authorities.

China has deployed several fighter jets and an advance warning aircraft into the area.

"We can't do this in the unilateral way China did and cause friction with neighbouring countries. How to inform neighbouring countries after our decision is finalised is also subject to discussion," said another South Korean government official.

South Korea has also pledged to take into account international maritime law.

It had expressed "strong regret" over China's actions.