North Korea said Thursday it promoted three senior officials involved in nuclear negotiations with the United States in a reshuffle ahead of its biggest political convention in decades.

First Vice Foreign Minister Kang Sok Ju, who negotiated a deal with the U.S. in 1994 to freeze and ultimately dismantle North Korea's nuclear reactor in exchange for economic aid, was promoted to vice premier, who oversees the country's foreign policy, the North's official Korean Central News Agency reported.

The legislature also promoted Pyongyang's top nuclear envoy, Kim Kye Gwan, and his deputy, Ri Yong Ho, to first vice foreign minister — the No. 2 position in the ministry — and vice foreign minister, respectively, KCNA said.

No reasons were given for their promotions in the brief KCNA dispatches, but the announcement came days before the North convenes its ruling Communist Party's biggest convention, where observers have speculated leader Kim Jong Il may promote his son to pave the way for his succession.

Delegates to the ruling Workers' Party will meet in Pyongyang on Sept. 28 to select their "supreme leadership body," KCNA said Tuesday.

Kim Kye Gwan was North Korea's top nuclear negotiator at the six-nation talks aimed at ending Pyongyang's nuclear programs. In 2005, the U.S., China, South Korea, Russia and Japan reached a new disarmament pact with the North — the 1994 deal with the U.S. had collapsed in 2002 when Washington accused the North of running a secret uranium enrichment program.

In 2009, North Korea quit the disarmament-for-aid talks, and then conducted a nuclear test that drew tightened U.N. sanctions.

The Foreign Ministry reshuffle was not expected ahead of the convention, but Kim Jong Il reportedly expressed interest in rejoining nuclear talks while on a trip to China.