North Korea will face additional U.N. Security Council sanctions further deepening its isolation if the regime forges ahead with a banned long-range rocket launch, South Korea's chief nuclear envoy said Wednesday.

Special representative Hwang Joon-kook made the remark after talks with his U.S. counterpart, Amb. Sung Kim, in Washington, stressing that a satellite launch by the North, unlike those by other nations, constitutes a clear violation of U.N. resolutions.

"The right to peaceful use of space, which is possessed by ordinary nations, is clearly restricted in the case of North Korea under Security Council resolutions. In other words, North Korea's satellite launch is considered a test aimed at advancing its nuclear weapon delivery capabilities," Hwang told reporters.

"Should North Korea push ahead with the so-called satellite launch, it will bring about additional measures by the Security Council and would be putting itself in deeper isolation," he said.

On Monday, the North strongly hinted at the possibility of launching a long-range rocket around the Oct. 10 anniversary of the ruling Worker' Party, saying its scientists are working hard to mark the anniversary with greater achievements than the country's successful 2012 satellite launch.

Arguing it has the right to the peaceful use of space, it also vowed to keep launching satellites.

The missile threat was followed a day later by a nuclear threat.

The North said Tuesday that its bomb-making nuclear facilities at the Yongbyon complex have returned to normal operation and are ready to respond to U.S. "hostile policy" toward it with "nuclear thunder," a term apparently referring to a nuclear test.

Hwang said South Korea and the U.S. share "deep concern" about the possibility of the North's rocket launch, saying the communist nation "has openly stated that it will possess missile capabilities to strike as far as the mainland U.S."

"Not only six-party countries, including South Korea and the U.S., but also the U.N. Security Council take this dangerous move by North Korea as a serious act of threatening peace," the envoy said. "North Korea should remember that it is the only country subject to U.N. Security Council resolutions due to its development of weapons of mass destruction."

Hwang also urged the North to return to the negotiating table, saying Seoul and Washington are ready to hold "exploratory talks"

with Pyongyang without any conditions to test the North's commitment to denuclearization before formally restarting the six-party talks.

North Korea has conducted three underground nuclear tests so far, in 2006, 2009 and 2013. The country has also conducted a series of long-range missile or rocket launches since 1998. In its most recent launch in late 2012, the North succeeded in putting a satellite into orbit.

Analysts have warned that it is only a matter of time until the North develops nuclear-tipped missiles. Some experts have warned earlier this year that the communist nation's nuclear arsenal could expand to as many as 100 bombs by 2020.

The six-party talks aimed at resolving the North Korean standoff have been stalled since late 2008. North Korea demands the unconditional resumption of negotiations, while the U.S. says that Pyongyang must first take concrete steps demonstrating its denuclearization commitments. (Yonhap)