Former Mongolian President Punsalmaagiin Ochirbat has said North Korea's simultaneous pursuit of nuclear weapons and economic development is an "impossible" task, adding that Pyongyang should first give up its nuclear program to seek economic growth.

Ochirbat, who served as Mongolia's first directly elected president from 1990 to 1997, said economic cooperation with North Korea will be impossible, unless the reclusive state gives up its nuclear program.

"North Korea needs to focus on enhancing its relationships and economic cooperation with neighboring countries to boost its economy," Ochirbat said in an interview with Yonhap News Agency.

The interview was held at his office in Ulaanbaatar last Thursday ahead of South Korean President Park Geun-hye's visit to Mongolia from July 14-18. "Nuclear development should not be the North's priority."

Ochirbat has been an important figure in building the relationship between South Korea and Mongolia. During his presidency, South Korea and Mongolia established diplomatic ties in 1991. In the same year, he also became the first Mongolian leader to visit South Korea.

Ochirbat is also known for leading denuclearization in his country. In 1992, he declared Mongolia as a "nuclear-weapon-free zone," at the United Nations General Assembly.

Ochirbat previously said national security comes from the country's wealth, not from nuclear arms, and urged the North to open its doors to feed its own people. The 74-year-old said his thoughts on national security haven't changed.

"Before the 20th century, military power determined national security," he said. "But now in the 21st century, defending national security with arms and nukes are old ideas."

Ochirbat urged North Korean leader Kim Jong-un to make decisions on reforms and open up markets. He said Kim should follow the philosophy of his late grandfather Kim Il-sung that the country should expand its railway network. Ochirbat noted that since the North's railway networks are already established, there should be no additional time or investment needed to construct new ones.

"I know Koreans have a tradition of inheriting their ancestor's philosophy," he said. "The current leader of North Korea should acknowledge his grandfather's idea of connecting railways with Russia, China and Eurasia will give a big boost to its economy, and he should execute the plan."

During his term in office, Ochirbat led Mongolia to break the country from its socialist past and adopt capitalism. He claimed the two Koreas should join its new "Silk Road Express" project that connects the Korean Peninsula, China, Mongolia and Europe in a railway.

"If a railway starting from Busan can go through China, Mongolia and Russia, and reach Berlin and Paris, it will be a big economic opportunity for both South and North Korea," he said. "The Korean Peninsula and Northeast Asia should lead the economic development of Eurasia." (Yonhap)