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However, she also mentioned that the United States and China had to take their share of responsibility.
Speaking at a news conference, Leuthard said, "We are ready to offer our role... as a mediator."
"It is really time now to sit down at a table. Big powers have a responsibility," she added.
Meanwhile, the US top United Nations representative has said that North Korea is "begging for war" and urged UN Security Council to impose "the strongest possible measures" on Pyongyang over its sixth and largest nuclear test.
"To the members of the UN Security Council I must say - enough is enough.The time for half-measures in the Security Council is over.We must now adopt the strongest possible measures", Sputnik quoted US ambassador to the UN Nikki Haley as saying during an emergency meeting of the UN Security Council over the recent hydrogen bomb test by North Korea.
"Kim Jong-un's abusive use of missiles and his nuclear threats show that he is begging for war. War is never something the United States wants. We don't want it now. But our country's patience is not unlimited," she added.
UN Under-Secretary-General for Political Affairs Jeffrey Feltman dubbed North Korea's nuclear tests as dangerous provocation and said that Pyongyang has undermined the international non-proliferation efforts.
"We are alarmed by this dangerous provocation. The secretary-general condemns the underground nuclear test announced by the DPRK. This act is yet another serious breach of the DPRK's international obligations and undermines international non-proliferation and disarmament efforts," he said.
Japan's UN Ambassador Koro Bessho called for the UNSC to adopt swiftly a new resolution with further robust sanction measures against Pyongyang.
He said that the UNSC must act to stop North Korea from continuing such actions and should put maximum pressure to change its policy.
He further said that North Korea's nuclear test was an outrageous and unacceptable challenge to the security and safety of the world.
The news reader of the North Korean Central Television said that North Korea's leader Kim Jong Un ordered the test and termed it a "perfect success". The quake was felt in northern China, with emergency sirens blaring in Yanji, near the North Korean border, according to local media.