BEIJING -- China's foreign ministry on Friday refused to confirm or deny U.S. Secretary of State Rex Tillerson's assertion that Beijing has threatened to impose unilateral sanctions on North Korea if it conducts further nuclear tests.

Ministry spokesman Geng Shuang repeatedly avoided giving a direct answer when asked about the matter at a daily press briefing.

Tillerson said Thursday that China told the U.S. it had informed North Korea China would respond to a test by "taking sanctions actions on their own."

China wants North Korea to end its nuclear weapons program, but has opposed unilateral sanctions imposed without a UN mandate.

Beijing has come under growing U.S. pressure to use its leverage as North Korea's largest trading partner and main source of food and fuel aid to compel Pyongyang to heed UN resolutions.