The emergency meeting of the body charged with global peace and security came amid fears that North Korea will resume nuclear testing in the coming weeks.

"It is time to stop providing tacit permission and start taking action," US ambassador to the UN Linda Thomas-Greenfield said. "We need to turn quickly to strengthening the... sanctions regime, not considering sanctions relief."

Thomas-Greenfield rejected a draft resolution from China and Russia, like the US both veto-wielding members of the council, which aims to ease sanctions imposed in 2017.

Instead, she said they were near the end of negotiations on a separate US text updating the sanctions.

"We cannot wait until (North Korea) conducts additional provocative, illegal, dangerous acts like a nuclear test. We need to speak up now," she said.

Chinese ambassador to the UN Zhang Jun called the possibility of escalation "worrying" and called for "restraint," adding that tightening sanctions in an atmosphere of mistrust was "not constructive."

"What China wants to avoid is a new nuclear test," he told AFP after the meeting.

"So that's why we do not want to have additional sanctions that might force one of the parties to take more proactive action.

"Talking is better than coercive measures. We have seen so much coercive measures in the world, in Syria, in Iraq and Afghanistan. Have you seen any good results? What we have seen is only the humanitarian suffering."

Russia's Deputy Ambassador Anna Yevstigneeva also advocated the resolution proposed with China and called for the resumption of dialogue.

Pyongyang has dramatically ramped up its sanctions-busting missile launches, conducting more than a dozen weapons tests since January including firing an intercontinental ballistic missile at full range for the first time since 2017.

Wednesday's Security Council meeting came one day after the swearing in of South Korea's hawkish new president Yoon Suk-yeol, who has vowed to get tough on Pyongyang.

Satellite imagery meanwhile indicates North Korea may also be preparing to resume nuclear testing, with the US State Department last week warning a test could come "as early as this month."