MOSCOW, July 6 (RIA Novosti) - Poverty-stricken North Korea has spent an estimated $700 million on nuclear and missile tests since the beginning of 2009 in defiance of UN sanctions, a South Korean newspaper said on Monday.

Despite being in dire economic straits, the reclusive communist regime conducted an underground nuclear test on May 25, and has conducted a total of 18 missile launches since January 1, including a long-range rocket launched in April, nine ground-to-ship missiles, seven medium-range surface-to-surface ballistic missiles, and one surface-to-air missile, the Chosun Ilbo newspaper said.

According to South Korean estimates, the cost of the nuclear test alone could be anywhere between $300-400 million.

The paper quoted a South Korean government official as saying that $300 million "could have been spent to buy 1 million tons of rice in the international market at the exchange rate of last summer. This amount of rice could have solved the North's food shortage for about a year."

According to a UN report on North Korea last year, at least 9 million people, or about one third of the population, were in desperate need of food aid.

North Korea is banned from conducting nuclear tests or launching ballistic missiles under UN Resolution 1718, which was adopted following the country's first nuclear test on October 9, 2006. Pyongyang is also subject to a series of UN sanctions aimed at forcing it to terminate its controversial nuclear program.

Meanwhile, the North has withdrawn from six-nation nuclear talks, also involving the United States, Russia, China, Japan, and South Korea, that could have resulted in substantial economic and food aid to the impoverished nation.

The Russian Foreign Ministry expressed on Monday "regret" over a series of new missile launches conducted by North Korea and urged Pyongyang to return to the negotiation table.

"We urge Pyongyang not to carry out new steps that could deteriorate an already tense situation in the region, and return to the negotiation table," spokesman Andrei Nesterenko said.