New Zealand Foreign Minister Murray McCully offered condolences on Thursday and said New Zealand is ready to support China humanitarian response to Wednesday's devastating earthquake in China's Qinghai Province.

"While details are still emerging, it is already clear that there has been significant loss of life and destruction caused by the 6.9 quake and aftershocks in Qinghai province," McCully said in a statement.

"I have written personally to senior leaders in China offering the sincere sympathy and condolences of the people of New Zealand to those affected by the earthquake," he added.

"New Zealand stands ready to offer whatever useful support that we can should China request assistance," McCully said.

McCully made an official visit to China on March 22-26.