Malaysia will use the diplomatic approach in handling the territorial disputes over the South China Sea, said Deputy Prime Minister Datuk Seri Dr Ahmad Zahid Hamidi.

This, he said, was appreciated by China's President Xi Jinping.

"Our approach is for a diplomatic solution as mentioned by the Prime Minister (Datuk Seri Najib Tun Razak), and the Chinese President appreciated the effort taken by the Malaysian government," he said.

Ahmad Zahid, who is also home minister, spoke to reporters after opening the ASEAN+ Young Leaders Summit at the Putra World Trade Centre here today.

The minister was asked to elaborate on his statement criticising a "regional superpower" for encroaching into Malaysia's maritime territory by constructing airstrips, jetties and other facilities off Sabah.

Beijing has in recent months claimed ownership of several disputed atolls in the South China Sea and reportedly built runways and other facilities on the islands.

On the threat posed by the IS militant group in view of the 27th ASEAN Summit hosted by Malaysia, Ahmad Zahid said the country's security forces were on the alert.

"We are fully alert (to the threat by the IS). Our anti-terrorist teams are moving around and monitoring communication," he said.

The police and other security forces had stepped up security for leaders attending the 27th ASEAN Summit and Related Summits following the terror attacks in Paris last Friday, he said.

Ahmad Zahid also said that he hoped that the people of Kuala Lumpur would bear with the traffic congestion in the city following the closure of several roads in conjunction with the summits.