The U.N. Security Council announced late Monday evening that it will hold closed consultations on North Korea and non-proliferation at 11 a.m. (1600 GMT) Tuesday. The diplomats, speaking on condition of anonymity because no official announcement has been made, said the United States is expected to circulate a draft resolution to the full council at the meeting. Council members are then expected to send the draft to their capitals for review.
All 15 council members approved a press statement condemning Pyongyang's nuclear test and pledging further action hours after North Korea carried out its third atomic blast on Feb. 12.
The swift and unanimous response from the U.N.'s most powerful body set the stage for a fourth round of sanctions against Pyongyang.
For the last three weeks, the United States, a close ally of South Korea and Japan, has been negotiating the text of a new resolution with China, North Korea's closest ally.
Russian U.N. Ambassador Vitaly Churkin, whose country holds the council presidency this month, told a news conference Monday that a resolution on North Korea might be approved in March though the text had not yet been circulated.
A Chinese Foreign Ministry spokeswoman in Beijing refused to give any details about the deal at her daily media briefing, but indicated China was concerned about Pyongyang's behavior.
"We have said here many times that China supports the U.N. Security Council in reacting moderately and explicitly objects to North Korea's nuclear test," spokeswoman Hua Chunying said.
In Seoul, a Foreign Ministry spokesman said Tuesday that "considerable progress" has been made in the Security Council on how to punish North Korea for its latest nuclear test. However, spokesman Cho Tai-young told reporters he couldn't disclose any details of the draft resolution because no final agreement has been reached.
Last month's statement from the Security Council called the underground test in February a "grave violation" of three U.N. resolutions that ban North Korea from conducting nuclear or missile tests.
North Korea's three nuclear tests -- in 2006, 2009 and 2013 -- occurred after Pyongyang was condemned by the United Nations for rocket launches.
The Security Council imposed sanctions after the first two nuclear tests and after the North's rocket launch in December, which was viewed as part of the country's covert program to develop ballistic missiles that can carry nuclear warheads.
The sanctions are aimed at trying to derail the country's rogue nuclear weapons and ballistic missile programs. They bar North Korea from testing or using nuclear or ballistic missile technology, and from importing or exporting material for these programs.
The latest sanctions resolution, adopted in January, again demanded that North Korea abandon its nuclear weapons program and cease missile launches. It slapped sanctions on North Korean companies and government agencies, including its space agency and several individuals.
The diplomats said they did not know what new sanctions would be included in the resolution to be circulated Tuesday.
There has been speculation that a new resolution will strengthen existing sanctions related to North Korea's nuclear and missile programs, toughen financial restrictions and cargo inspections, and add additional companies and individuals to the sanctions list.
Any fresh international sanctions are certain to infuriate North Korea, which has claimed the right to build nuclear weapons to deter alleged U.S. aggression.
After its successful Feb. 12 atomic test, the North's Foreign Ministry said the test was aimed at coping with what it called U.S. nuclear threats and warned that the country would take unspecified "second and third measures of greater intensity" if Washington maintains its hostility.
Pyongyang has blamed Washington for leading efforts to impose the toughened U.N. sanctions for December's rocket launch that it says was only aimed at sending a satellite into space.
North Korea and the U.S. are still technically at war because the 1950-53 Korean War ended with an armistice, not a peace treaty. The U.S. deploys about 28,500 troops in South Korea to protect its ally. Pyongyang has long accused Washington and Seoul of plotting to invade the country, though the allies have repeatedly said they have no intentions of attacking the North.
The North's latest nuclear test was seen as a crucial step toward its goal of building a bomb small enough to be fitted on a missile capable of striking the United States. Many outside analysts still believe the North hasn't achieved such a miniaturization technology.
Associated Press writers Hyung-jin Kim in Seoul and Louise C. Watt in Beijing contributed to this report.
Copyright 2013 The Associated Press.