The meeting was requested by Ukraine and backed by Western Security Council members.
The United Nations Security Council will convene for its second emergency session in three days over the Ukraine-Russia crisis, "due to military developments" on the ground, diplomatic sources said.
The meeting, which was requested by Kyiv earlier Wednesday and backed by Western Security Council members, is scheduled for 9:30 pm (0230 GMT Thursday), the sources said.
In the letter requesting the meeting, seen by AFP, Ukraine's ambassador to the UN, Sergiy Kyslytsya, underscored that there was an "immediate threat of a Russian offensive" and that separatists in eastern Ukraine had "requested military assistance" from Russia.
The diplomat asked that Ukraine be represented at the meeting and requested a briefing on the situation by UN Secretary-General Antonio Guterres.
Like the previous emergency meeting on the crisis held on Monday, the session will be chaired by Russia, currently president of the Security Council.
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