The UN Security Council will hold closed-door consultations tomorrow to discuss a possible condemnation of North Korea's latest ballistic missile launches, UN diplomats said.
The request for a special session on North Korea came from the United States.
The meeting of the 15-nation council was scheduled for tomorrow night.
In what appeared to be a show of defiance, North Korea fired two medium-range Rodong ballistic missiles into the sea yesterday, both Tokyo and Seoul said.
North Korea's first firing in four years of mid-range Rodong missiles that can hit Japan followed a series of short-range rocket launches over the past two months.
UN Secretary-General Ban Ki-moon's press office issued a statement condemning the latest missile launch.
"Such launches are contrary to building trust in the region. The Secretary-General urges the DPRK (North Korea) to cease its ballistic missile activities and focus, together with other countries concerned, on the dialogue and diplomacy necessary to maintain regional peace and security," the statement said.
Council diplomats said Washington was expected to propose a Security Council statement that would condemn the missile firings.
It was not clear whether China, Pyongyang's protector on the council, would support such a condemnation, though it has been willing to back rebukes of Pyongyang in the past.
Deputy US State Department spokeswoman Marie Harf said yesterday: "We are closely coordinating with our allies and partners, including in the UN Security Council, to take the appropriate measures in response to this latest provocation and to address the threat to global security posed by the DPRK's nuclear and ballistic missile programmes."
There is also a possibility, the diplomats said, of the Security Council's North Korea sanctions committee eventually expanding the current UN blacklist to include additional North Korean entities involved in Pyongyang's missile program.
Expansion of the blacklist would take more time and was not expected to be decided tomorrow, the diplomats said.
According to diplomats, ballistic missile launches are banned under UN Security Council resolutions adopted in response to North Korea's 2006 and 2009 nuclear tests and subsequent rocket firings.
Those resolutions imposed a series of UN sanctions on Pyongyang that target the country's missile and nuclear programmes and attempt to punish North Korea's reclusive leadership through a ban on luxury goods.
The US said that North Korea's test firing of the medium-range missiles represents "a troubling and provocative escalation" on the Korean Peninsula.
The North's action came as US President Barack Obama hosted a landmark Japan-South Korea summit and pledged his "unwavering commitment" to Tokyo and Seoul in the face of Pyongyang's nuclear threat.
Over the past four weeks, North Korea has conducted multiple launches of short-range Scud missiles and rockets to coincide with the annual joint military drills that South Korea is conducting with the US.
South Korea has condemned the Scud launches as a "reckless provocation", but stopped short of calling for UN sanctions, given the short range and a recent easing of North-South tension.
The North Korean military had defended the tests as "ordinary military practice".