South Korea's ruling party chief crossed the border into North Korea to tour a joint inter-Korean industrial complex on Friday, a move seen as an attempt by Seoul to improve strained ties with Pyongyang.

Tensions still linger between the two divided Koreas over the North's two deadly attacks on the South last year that killed 50 South Koreans, mostly soldiers.

The North has refused to take responsibility for the attacks, keeping the rival Koreas from repairing their relations for more than a year.

The one-day trip by Rep. Hong Joon-pyo, chairman of the ruling Grand National Party, comes after he called for Seoul to exercise flexibility on its policy toward Pyongyang to try to improve their frayed ties.

Hong also recently proposed a project to help the North's agricultural sector.

"I'm the first chief of the Grand National Party to visit the Kaesong complex. This is a working visit, but it is a politician's obligation to break the stalemate in inter-Korean relations," Hong told reporters before crossing the border.

It was not immediately clear whether Hong will meet with senior North Korean officials in the North's western border city of Kaesong for talks on how to end the inter-Korean political deadlock.

The factory park has become the last-remaining symbol of inter-Korean rapprochement that boomed following their first-ever summit in 2000.

More than 47,000 North Koreans work at about 120 South Korean firms operating in the industrial zone to produce clothes, utensils, watches and other goods. The project serves as a key legitimate cash cow for the impoverished communist country.

The trip also comes amid diplomatic efforts to move forward long-stalled talks on ending North Korea's nuclear weapons programs.

Last week, the nuclear envoys of South and North Korea held their second meeting in Beijing in as many months, although no significant progress was made.

North Korea calls for an early resumption of the talks without any preconditions but Seoul and Washington insist that Pyongyang halt its uranium enrichment program and allow U.N. inspectors back into the country before resuming the talks.

The six-party talks, which involve the two Koreas, the United States, China, Japan and Russia, were last held in Beijing in late 2008. (Yonhap News)