"It is China in the end that decides Kim Jong-Il's fate," he continued. "South Korea must sign a free trade pact with China to draw China and North Korea apart and fully isolate the North Korean economy," he said.
"It's necessary to call China to account for maintaining an alliance with Kim Jong-Il," he said.
Without the bilateral alliance, China could increase leverage on the North, the defector said.
"Opening and reform after the Chinese model are tantamount to getting rid of absolute rule in the North and introducing the market economy,” Hwang said. “If this happens, North Korea's living standards would improve dramatically within 15 years.
Hwang stressed the need for Seoul to also form free-trade agreements with other Asian nations, including Thailand, which also trades with North Korea.
Hwang accused China of seeking to increase its international influence by making use of the North Korean nuclear issue.
China recently sent Premier Wen Jiabao to Pyongyang to offer massive economic projects and a donation worth $200 million in return for Kim’s promise to consider rejoining long-stalled six-nation talks on the North’s nuclear issue.
“China wants to keep the six-party talks afloat and use the multilateral dialogue to make the United States, South Korea and Japan be more dependent on Beijing’s role in resolving the nuclear standoff,” Hwang said at meeting following the forum.
The six-party talks brought together the two Koreas, China, the United States, Japan and Russia, and was established to negotiate an end to Pyongyang's nuclear weapons programs in exchange for aid and diplomatic incentives. China has hosted the forum since its inception in 2003.
North Korea is unlikely to be thrown into chaos, even if its ailing leader Kim Jong-Il dies because China would maintain firm control over it, Hwang said.