North Korea has invited the chief U.S. negotiator to the six-way nuclear talks, Christopher Hill, to Pyongyang for talks on resolving the stalemate.

In a statement issued by the spokesman of the North Korean Foreign Ministry Thursday, Pyongyang said its "independent" socialist economy will not be shaken by Washington's financial sanctions.

Pledging to collect every last penny "snatched" by the United States, the statement said the North will have no choice but to take ultra-tough measures to protect its right to survival and independence if U.S. pressure on Pyongyang increases.