FILE PHOTO: North Korean soldiers chat as they stand guard behind national flags of China (front) and North Korea on a boat anchored along the banks of Yalu River, near the North Korean town of Sinuiju, opposite the Chinese border city of Dandong, June 10, 2013. REUTERS/Jacky Chen

BEIJING (Reuters) - China’s foreign ministry said on Monday it had lodged “solemn representations” with the North Korean embassy in Beijing over the North’s sixth and most powerful nuclear test.

North Korea is clear about China’s opposition to its nuclear tests, ministry spokesman Geng Shuang told a regular briefing, adding that China upholds talks as the means to resolve the Korean peninsula issue.

The North said it tested an advanced hydrogen bomb for a long-range missile on Sunday, prompting a vow of “massive” military response from the United States if either it or its allies were threatened.