Bolton, under secretary of state for arms control and international security, held a series of closed-door sessions with minister Ban Ki-Moon and other top security officials, the ministry said.

US officials said a key focus of Bolton's discussions in Seoul and in Tokyo, which he visits from Thursday, would be the US-led international drive to curb the spread of weapons of mass destruction.

Considered one of Washington's more hawkish critics of Pyongyang, Bolton last year called North Korean leader Kim Jong-Il a "tyrannical rogue" and described life in the Stalinist state as a "hellish nightmare".

In return Pyongyang branded him "human scum."

The talks were to focus on "a variety of non-proliferation issues, including North Korea," the US embassy said in a statement.

Bolton, who arrived in Seoul on Monday for a four-day visit, is to give a speech about denuclearizing North Korea at a Seoul university and hold a press conference Wednesday, the embassy said.

The North Korean regime has attacked a Washington-led scheme pushed by Bolton to crack down on trafficking in weapons of mass destruction by land sea or air that targets Pyongyang and other so-called rogue states or groups.

Established in May last year by US President George W. Bush, the Proliferation Security Initiative groups some dozen countries including Russia.

South Korea, unwilling to upset North Korea, has been reluctant to sign on to the initiative whose members have pledged to crack down on trafficking in nuclear weapons, their components, and delivery systems.

Seoul is seeking to engage North Korea despite the long-running nuclear stand-off that erupted in October 2002 when Washington accused North Korea of running a nuclear weapons scheme.

Bolton's visit comes amid guarded optimism following a third round of six-party talks last month at which the US softened its demand for the complete dismantlement of North Korea's weapons drive before it would engage in talks.

WAR.WIRE