US Ambassador Nikki Haley on Monday slammed Venezuela as an "increasingly violent narco-state" that poses a threat to world security at a UN meeting boycotted by Russia and China.

Haley said the informal Security Council meeting was to draw international attention to the political and economic crisis in Venezuela, which is teetering on the brink of default.

But key Security Council members Russia and China refused to attend as did Bolivia, a non-permanent council member close to President Nicolas Maduro's government, and Egypt.

Addressing the meeting, Haley said "the situation in Venezuela is more than a human tragedy," adding that the crisis "poses a direct threat to international peace and security."

"Venezuela is an increasingly violent narco-state that threatens the region, the hemisphere and the world," she said.

Addressing reporters outside of the meeting hall, the ambassadors of Russia, China and Bolivia joined Venezuela's UN envoy, who declared the meeting "illegal" and a violation of the UN charter.

"This is a hostile act by the United States and clearly an act of interference," said Venezuela's Ambassador Rafael Ramirez.

Russian Ambassador Vassily Nebenzia said the US-led talks amounted to "meddling in the domestic affairs of Venezuela" and declared that the Security Council should not become involved.

The refusal by Russia and China to attend the meeting meant that the United States would face strong opposition in pushing for council action to address the crisis in Venezuela.

Venezuela has been in turmoil since anti-government protests in April left more than 100 dead as the country reels from shortages of food and medicine.

On Monday, the Caracas government was meeting with credits in a bid to stave off a default from $150 billion in debt.

Over 600,000 Venezuelans have moved across borders in the region this year alone, citing fears of crime, repression and food insecurity, UN High Commissioner for Human Rights Zeid Ra'ad Al Hussein told the meeting.

"If no steps are taken to confront the serious human rights violations in Venezuela, I am very much concerned about the negative destabilizing effect it could have on the region as a whole," he said.

Haley said the fact that Venezuela had exerted pressure on council members not to attend the meeting was "proof" of "guilt."