SEOUL • China and South Korea have agreed to slap tougher sanctions on North Korea if it carries out nuclear or long-range missile tests, a senior official in Seoul said yesterday as a US Navy strike group headed to the region in a show of force.

North Korea marks several major anniversaries this month and often marks such occasions with major tests of military hardware.

South Korea's chief nuclear envoy Kim Hong Kyun said there was no mention of any military option in his talks with China's Special Representative for Korean Peninsula Affairs Wu Dawei. The two also did not discuss any possible strike against the North by the Trump administration, he said.

"Both sides agreed that despite the international community's warnings, if North Korea makes strategic provocations such as a nuclear test or an ICBM (intercontinental ballistic missile) launch, there should be strong additional measures in accordance with UN (United Nations) Security Council resolutions," he said.

Mr Kim added that the two sides agreed "an even stronger UN resolution" would have to be adopted in the event of additional weapon tests by North Korea. Mr Wu did not speak to reporters.

Mr Wu's trip was the first visit to South Korea by a senior Chinese official after the planned deployment of the United States Terminal High Altitude Area Defence (Thaad) missile defence system led to a diplomatic row between Beijing and Seoul. Mr Kim said Mr Wu repeated China's position on the Thaad deployment but did not give details.

China has previously said the system would destabilise the regional security balance and that its radar's reach would be intruding into Chinese territory.

Meanwhile, US Secretary of State Rex Tillerson has said the US military strike against Syria last week over its alleged use of chemical weapons was a warning to other countries, including North Korea, that "a response is likely" if they pose a danger. Chinese President Xi Jinping "clearly understands, and I think agrees, that the situation has intensified and has reached a certain level of threat that action has to be taken", he said on Sunday.

At a summit meeting in Florida last week, US President Donald Trump pressed Mr Xi to do more to curb Pyongyang's nuclear programme. China is North Korea's main diplomatic and economic ally.

Mr Tillerson on Sunday also said Washington was not interested in "regime change" in North Korea, while reiterating that it must stop all weapon testing before further diplomatic talks can take place.

Mr Tillerson yesterday briefly met Japan's Foreign Minister Fumio Kishida in Italy ahead of a two- day meeting of Group of Seven foreign ministers, which was likely to be dominated by the Syrian issue.

Mr Kishida said he told Mr Tillerson that Japan supports the US in its push to "deter the spread and use of chemical weapons", and they discussed the pressing North Korean nuclear threat. Japan hopes the strong US response over Syria would also put pressure on Pyongyang. "We agreed that the role of China is extremely important. Japan and the US will jointly call on China to play a bigger role," Mr Kishida said.

REUTERS, AGENCE FRANCE-PRESSE