BEIJING (REUTERS) - China has agreed that "pressure"on North Korea is an important element in a push for denuclearisation on the Korean peninsula, a US official overseeing policy on North Korea said on Friday.

US Secretary of State John Kerry said last week the United States and China were discussing imposing further sanctions on North Korea, which he said was "not even close" to taking necessary steps to end its nuclear programme.

China is North Korea's most important trading partner and only major ally, though the North's nuclear and missile tests over recent years have strained their ties. "The Chinese agree that pressure has to be an important part of our approach on North Korea," Sung Kim, the US special representative for North Korea policy, told a media briefing in Beijing.

Chinese government spokesmen were not immediately available for comment. China has always called for "denuclearisation" of the whole Korean peninsula, including any weapons held by US forces in South Korea, being careful not to point the finger of blame solely at the North.

Kim represented the United States in talks this week with its two important Asian allies, South Korea and Japan, on how to step up pressure on North Korea to give up its nuclear ambitions. Those talks were in the South Korean capital, Seoul.

Kim also told the briefing in Beijing that the United States believed China was fully implementing sanctions on North Korea brought by the UN Security Council.

Kim's visit to the region follows a test of what the North said was a submarine-launched ballistic missile this month, which if true, could mean progress in the reclusive state's military capabilities.

North Korea's first nuclear test was in 2006. It tested again in 2009, and more recently in 2013, drawing criticism from many countries including China.

It has defied pressure to abandon its missile and nuclear programmes.