A North Korean factory worker has been executed by firing squad for sneaking news out of the country on his illicit mobile phone, Seoul-based radio said today.

The armaments factory worker was accused of divulging the price of rice and other information on living conditions to a friend who had defected to South Korea years ago, Open Radio for North Korea reported.

The man, surnamed Chong, made calls to the defector using an illegal Chinese mobile phone, according to an unnamed North Korean security agency official cited by the report.

The execution took place by firing squad in late January in Hamhung, according to Open Radio for North Korea. The station broadcasts into North Korea, which tightly controls news.

South Korea's unification ministry, which handles relations with North Korea, and the national intelligence service, Seoul's main spy agency, said they could not immediately confirm the report.

Mobile phone use in North Korea is tightly restricted, although the country introduced an advanced network in partnership with Cairo-based Orascom Telecom in 2008. North Koreans who manage to make illegal overseas mobile calls mostly use networks in China.

Open Radio for North Korea said it believes that more than 10,000 North Koreans living near the border with China illicitly possess Chinese mobile phones.

Ha Tae-keung, the broadcaster's chief, said it was not known to whom in South Korea the information passed on by Chong was eventually delivered.

The North Korean defector said to have received the calls, only identified by the common Korean family name of Kim, may have worked for South Korean government officials, researchers or news outlets, Ha said.

Ha said neither the executed man nor the defector had worked for Open Radio for North Korea.