Secretary-General Ban Ki-moon says he has never seen tensions on the Korean peninsula as high as they are today and he's calling on the U.N. Security Council to take urgent action to prevent "provocative actions" by North Korea.

Ban, a former South Korean foreign minister, told a news conference Wednesday that U.S. Ambassador Samantha Power has already begun work on a new U.N. resolution with key council members including China.

He said it's urgent that the council unite, "show firm resolve" and commitment, and not lose time in sending a strong message to North Korea that their nuclear tests and ballistic missile launches are unacceptable and must stop.

Ban said the council has met eight times this year on North Korea reflecting "the seriousness and gravity" of the situation.