By Jack Kim
SEOUL (Reuters) - South Korea's main left wing opposition party, which polls say is headed for a victory in an April parliamentary election, vowed on Tuesday closer ties with North Korea and will end a sanctions regime imposed by the current conservative government.
The move comes amid saber-rattling by North Korea after it held talks with the United States last week on its nuclear program and food aid, the first under its new leader Kim Jong-un.
Incumbent President Lee Myung-bak put an end to a decade of aid to the North when he came to power in 2008, demanding the impoverished country abandon its nuclear ambitions, ending the "Sunshine Policy" of engagement by his two left-of-centre predecessors.
"The Lee Myung-bak government's North Korea policy, the policy of just waiting for the North to change, has failed," the leader of the opposition Democratic United Party, Han Myeong-sook told a forum.
The Democrats have led the conservatives since early last year in opinion polls, although the gap has narrowed in recent weeks. A poll by Realmeter published on February 17 showed the Democrats with 38 percent support versus the conservatives' 33 percent.
Two years after Lee took office a torpedo attack sunk a South Korean navy ship in disputed waters, killing 46 sailors. Seoul blames Pyongyang for the attack and tightened its sanctions regime further, banning commercial activity, visits and most trade.
"The Democratic United Party will actively pursue normalization of South-North ties and their improvement," Han said, adding that the sanctions imposed by Seoul would be removed as it sought a rapprochement with the new leader in Pyongyang, who is believed to be in his late 20s.
Kim Jong-un is the son of the former leader Kim Jong-il who died suddenly in December having built a state with nuclear weapons capacity and presided over a famine that killed millions of North Koreans in the 1990s.
Although a smiling and joking Kim, the third of his line to hold power in the North, appears to have enjoyed a stable ascent to power, the emphasis of his public appearances has been on the country's armed forces, suggesting he is not ready to abandon his father's "military first" policy.
In recent weeks, the North has stepped up harsh rhetoric, threatening a "sacred war" against the South and the United States as the allies began annual military drills.
The two Koreas are technically still at war having signed only a truce, not a peace treaty, to end their 1950-53 conflict.
Park Geun-hye, the interim leader of South Korea's ruling conservatives, who is seen as a leading contender for president at a ballot in December, also called for more engagement with the North but said Pyongyang must stop breaking its promises made with the international community and with Seoul.
(Editing by David Chance and Sanjeev Miglani)