World Bulletin/News Desk

China responded cautiously on Thursday to a call by U.S. President Barack Obama for a broad coalition to root out ISIL militants in Iraq and Syria, saying "the world should fight terror but that the sovereignty of countries must be respected."

Obama also told Americans on Wednesday that he had authorised U.S. air strikes for the first time in Syria and more attacks in Iraq in an escalation of a campaign against ISIL.

Chinese Foreign Ministry spokeswoman Hua Chunying said the world was facing a terror threat that was a "new challenge" to international cooperation.

"China opposes all forms of terrorism, and upholds that the international community must jointly cooperate to strike against terrorism, including supporting efforts by relevant countries to maintain domestic security and stability," Hua told a daily news briefing when asked about Obama's comments.

"At the same time, we also uphold that in the international fight against terrorism, international law should be respected and the sovereignty, independence and territorial integrity of relevant nations should also be respected," she added.

"China is willing to continue increasing exchanges and cooperation on fighting terrorism with the international community on the basis of mutual respect and cooperation."

China has repeatedly expressed concern about the upsurge in violence in Iraq and the march of ISIL, but it has also opposed any outside military intervention in Syria.

In July, China's Middle East envoy said that Muslims from China's far western region of Xinjiang (East Turkestan) had gone to the Middle East for training and some may have crossed into Iraq.

Xinjiang, home to the Muslim Uighur people who speak a Turkic language, has been beset by unrest for years because of crackdown on religious and cultural rights of Uighurs.

China is Iraq's largest oil client, and its state energy firms, which include PetroChina, Sinopec Group and CNOOC Ltd, together hold more than a fifth of Iraq's oil projects after securing some of its fields through auctions in 2009.