By Ju-min Park and Jane Chung
SEOUL (Reuters) - Ukraine has revoked a Soviet-era deal that allowed visa-free travel for North Koreans, the latest setback for isolated North Korea which has been under growing pressure since the UN Security Council imposed toughened new sanctions in March.
A Ukraine government document seen by Reuters said that the government approved a decree on July 27 to terminate the pact with North Korea, a major buyer of Ukraine's flour, that had allowed visa-free travel between the two countries.
The document, signed by Ukraine Prime Minister Volodymyr Groysman, said the withdrawal of visa-waiver agreement would "prevent ineligible persons from entering Ukraine".
The Ukraine Embassy in Seoul did not have immediate comment.
A recent surge in fighting in eastern Ukraine, where Kiev is fighting pro-Russian separatists, and fresh tension in Crimea have raised concern that a fragile ceasefire agreed in Minsk in February 2015 could collapse.
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 UN sanctions.
European Union member state Malta recently denied visa extensions for North Korean workers, effectively expelling them, South Korea has said.
South Korea has been making diplomatic efforts to engage North Korea's old allies to press for change in North Korea.
Impoverished North Korea and the rich, democratic South are technically still at war after their 1950-53 conflict ended in a truce, not a treaty.
Earlier this year, Namibia halted ties with two North Korean state-run companies that had built a munitions factory and were involved in projects for its military to comply with U.N. sanctions on Pyongyang, according to Namibian media and the South Korean government.
Poland has not issued new visas for North Koreans this year amid concerns that Pyongyang may be subjecting its workers to conditions that violated their rights.
Singapore will impose visa requirements on North Korean visitors from October, its immigration authority said in July.
(Editing by Jack Kim and Nick Macfie)