UN Secretary-General Ban Ki-moon on Monday offered his "deepest condolences and sympathies" to the victims of a deadly earthquake that hit northwest China's Gansu Province Monday morning.

The UN chief made the remarks at an event held at the Chinese Permanent Mission to the United Nations on Monday evening.

"Let me express my deepest condolences and sympathies to many people who have been killed and wounded by yesterday's earthquake in Gansu Province [in China]," Ban said.

"Our thoughts are with the families of victims and wounded people," he said.

The secretary-general also expressed his belief that under the leadership of Chinese President Xi Jinping, there will be a speedy recovery for those who are affected by the earthquake.

"I sincerely hope that the people of China will be able to overcome this very tragic [incident]," Ban added.

At least 87 people in the city of Dingxi and two in the neighboring city of Longnan have been confirmed killed in the 6.6-magnitude quake that jolted the border of Minxian and Zhangxian counties.

Meanwhile, 422 aftershocks had been recorded in the quake-hit region, with the strongest measuring 5.6 in magnitude.