China's drafting of its first counterterrorism law is a domestic issue, China's Foreign Ministry said on Tuesday in response to comments made by the United States.

US President Barack Obama on Monday said he was concerned that the law would require technology firms to hand over encryption keys, the passcodes that protect data.

The formulation of a counterterrorism law is an important step of rule of law and combating terrorism. The content of the draft law is based on real experiences in the fight against terrorism and has taken into account lessons learned by other countries, spokesperson Hua Chunying said at a daily news briefing.

"The formulation of the counterterrorism law is China's internal affair. We hope the United States can calmly and objectively handle it," she said.

"Every country is taking measures to ensure their information is secure," Hua said.

She said China had always opposed network monitoring and supported the drawing up of cyber space rules within the United Nations framework.

In September 2011, China, together with Russia, Tajikistan and Uzbekistan, submitted an "International Code of Conduct for Information Security" to the 66th session of the UN General Assembly, which promoted such norms and rules.

An updated draft was proposed to the UN in January 2015, to promote peace and stability in cyber space and governance without interference in to the domestic affairs of other countries.