The United States and China will increase their cooperation in convincing North Korea to curb its nuclear ambitions, Rex Tillerson the US secretary of state said on Friday.

The decision follows Xi Jinping, the Chinese president's first state visit to the United States since the take over by the new administration.

Mr Tillerson said on Friday that whilst no specific action had yet been planned, Mr Xi, had agreed the nuclear programme had advanced to a serious stage.

The US has been urging a reluctant China to take stronger action against North Korea's continued nuclear ballistic missile tests.