North Korea has "not even come close" to initiating talks by taking the steps needed to rein in its nuclear weapons programme, US Secretary of State John Kerry has said.

Speaking in the South Korean capital, Seoul, on Monday, Kerry blamed North Korea for continuing to break promises, make threats and "show flagrant disregard for international law" by continuing provocative nuclear and missile activity while oppressing its own people.

He said North Korea's "horrific conduct" must be exposed and vowed to ratchet up pressure on Pyongyang to change its behaviour, particularly since it has rebuffed repeated attempts to restart nuclear talks.

The US secretary of state said that Washington continued to offer the isolated North the chance for an improved relationship in return for signs of a genuine willingness to end its nuclear programme.

"To date, to this moment, particularly with recent provocations, it is clear the DPRK is not even close to meeting that standard," Kerry said during a joint news conference with Yun Byung-se, South Korean foreign minister.

Analysis: Al Jazeera's Harry Fawcett on Pyongyang missile test

North Korea conducted its first nuclear test in 2006 and is now believed to have at least 10 such weapons despite some of the toughest international sanctions in existence.

It conducted its third nuclear test in February 2013, and US-based experts forecast that it could increase its nuclear arsenal to between 20 and 100 weapons by 2020.

The North recently tested what it said was a submarine-launched ballistic missile, raising regional tensions about the prospect of a heightened threat that already includes nuclear arms development and an arsenal of ballistic missiles.

Al Jazeera's Harry Fawcett, reporting from Seoul, said that Kerry also warned that the US may be willing to push for North Korea to be referred to the International Criminal Court to face allegations of human rights abuses.

Our correspondent said such an effort would be "nearly impossible", however, as the US would face serious opposition from China.

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 US.

Source: Al Jazeera and agencies