SEOUL/PYONGYANG, May 9 -- There would be little chance for the two countries on the Korean Peninsula to improve their stressed relations via bilateral talks as Seoul has turned down a rare olive branch from Pyongyang.

While delivering the work report of the central committee of the ruling Workers' Party of Korea on Sunday, Kim Jong Un, the top leader of the Democratic People's Republic of Korea (DPRK), proposed the two sides on the Korean Peninsula hold talks at all levels so as to remove misunderstanding and distrust.

Direct communication between the two sides came to a complete halt after the DPRK conducted its fourth nuclear test in January.

In early April, Pyongyang mentioned the need for "negotiations" with Seoul for the first time since the UN Security Council adopted tougher sanctions in response to the DPRK's alleged H-bomb test and a long-range missile launch in February.

In the three-hour speech aired by the state TV on Sunday, the DPRK leader, aside from mapping out an economic development plan for the country, also called for dialog and negotiations with the South for the sake of national reunification.

The two sides should respect each other and join hands to open up a new chapter for improving inter-Korean ties and the campaign for national reunification, he said.

Kim urged South Koreato drop the mentality of confrontation and legal and institutional barriers, and to take practical steps to facilitate the development of bilateral relations.

Seoul appeared resolute in turning down the offer, like what it did in April.

"The North's proposal is merely its propaganda drive with no sincerity as it speaks of inter-Korean dialogue while continuing to develop a nuclear arsenal," the unification ministry of South Korea said in a statement.

"South Korea and the international community have the same stance that North Korea should not be recognized as a nuclear-powered state," the statement said.

Meanwhile, Seoul urged Pyongyang to give up its nuclear weapons program, saying the Korean Peninsula denuclearization is the premise of peace talks between the two sides.

A day earlier, South Korean Foreign Minister Yun Byung-se phoned with U.S. Secretary of State John Kerry and agreed to mount pressure on the DPRK.

"(They) agreed to keep sending strong warning messages together with the international community to deter additional nuclear tests and provocations by the DPRK," the ministry said in a press release.

The two officials shared their assessment of the DPRK's ongoing party congress and the possibility of further "provocations" by Pyongyang, according to the release.

In his marathon speech on Sunday, the DPRK top leader also touched on the subject of the country's nuclear program.

While describing the DPRK as a "responsible nuclear weapons state," Kim said Pyongyang will strive for world denuclearization and faithfully fulfill obligations of nuclear non-proliferation.

The DPRK, as it has already made clear, will not resort to nuclear weapons first unless its sovereignty is encroached upon by any aggressive hostile forces with nuclear capability, Kim said.