By David Brunnstrom and Ju-min Park
SEOUL (Reuters) - The United States and China are discussing further sanctions on North Korea as it has "not even come close" to taking steps to rein in its nuclear weapons program, U.S. Secretary of State John Kerry said on Monday.
Speaking in the South Korean capital, Kerry said Washington had offered the isolated North the chance for an improved relationship in return for signs of a genuine willingness to end its nuclear program.
"To date, to this moment, particularly with recent provocations, it is clear the DPRK is not even close to meeting that standard," Kerry told a joint news conference with South Korean Foreign Minister Yun Byung-se.
"Instead it continues to pursue nuclear weapons and ballistic missiles."
DPRK are the initials of the North's official name, the Democratic People's Republic of Korea. North Korea is already under heavy UN, EU and U.S. sanctions for its missile and nuclear tests.
"With respect to the methodology for boosting sanctions and other things, we (the United States and China) are discussing all of that now. China has obviously an extraordinary leverage.
"We will have security and economic dialogue with the Chinese in Washington in June and that will be the moment where we will table some of these specific steps."
Pyongyang walked away from a 2005 deal with China, Japan, Russia, South Korea and the United States to end its nuclear program in return for diplomatic and economic rewards.
Then in 2012, weeks after signing a deal entering a moratorium on nuclear and long-range missile tests, the North launched a ballistic missile, effectively voiding the agreement that also promised U.S. food aid to the impoverished state.
The North recently tested what it said was a submarine-launched ballistic missile, raising regional tensions about the prospect of a heightened threat.
Kerry also said it was likely that the North would be referred to the International Criminal Court because of human rights violations.
The U.N. General Assembly has recommended that the North be referred to the tribunal for crimes against humanity after a U.N. inquiry detailed abuses in the country including prison camps and use of torture.
However, China, Pyongyang's chief ally, is likely to veto any Security Council bid to refer North Korea to the ICC, diplomats have said.
North Korea is technically still at war with the South after the 1950-53 conflict ended in a truce, not a peace treaty, and regularly threatens to destroy the South's major ally, the United States.
China never apportions blame for North Korea's nuclear development but regularly urges the "denuclearization" of the Korean peninsula.
(Writing by Jack Kim; Editing by Nick Macfie)