A top U.S. diplomat says a proposed resolution before the U.N. Security Council represents a major upgrade in sanctions against North Korea in response to its latest nuclear test and missile launch.

Ambassador Samantha Power says the draft is meant to ensure North Korea will be held accountable for its actions.

"It is a major upgrade and there will be, provided it goes forward, pressure on more points, tougher, more comprehensive, more sectors. It's breaking new ground in a whole host of ways," Power said before heading into a closed-door meeting where the U.S. planned to circulate the draft to all 15 council members.

The draft is the result of an agreement between the United States and China, North Korea's main ally.

Diplomats say the council is expected to vote on the resolution over the weekend.