By Vladimir Soldatkin

VLADIVOSTOK, Russia (Reuters) - South Korean President Park Geun-hye called on Russia and other major global players on Saturday to increase pressure on North Korea to abandon its nuclear program which could open the road for cooperation with Pyongyang.

"If we cannot prevent (North Korea's) development of nuclear weapons, the nuclear threat will become a reality soon," Park told a business forum attended by Russian President Vladimir Putin and Japanese Prime Minister Shinzō Abe in the Russian Far East city of Vladivostok.

"In order for Pyongyang to take the decision to abandon its nuclear program, it is important to give it a strong unified message."

Concerns about the threat posed by North Korea have spiralled since it conducted its fourth nuclear explosion in January and followed it up with a series of missile tests despite severe United Nations sanctions, which Pyongyang rejects as an infringement of its sovereignty.

In June, North Korea test-fired what appeared to be two mobile Musudan rockets, one of which climbed to 1,000 km (600 miles), or enough to fly more than 3,000 km (1,800 miles) down range.

On Aug. 24, Pyongyang also fired a submarine-launched ballistic missile (SLBM) toward Japan that traveled 500 km (311 miles).

"If North Korea abandons its nuclear program and chooses the path to openness, we, together with the international community, will be ready to actively support it," Park said.

(Writing in Moscow by Lidia Kelly; Editing by Kim Coghill)