SEOUL: A Seoul-based rights group said Monday it has supplied contacts in North Korea with satellite phones to expand news coverage of the secretive communist state and minimise the use of riskier cellphones.

Free North Korea Radio, run by North Korean defectors, said it gave satphones to "correspondents" in the North five months ago to try to break down the wall of secrecy.

Several rights groups in South Korea have contacts who relay news via Chinese cellphones with pre-paid cards, but these work only in border areas.

Free North Korea Radio, which broadcasts to the North on short wave as well as running an Internet service, said the satphones give it access to information from more parts of the country.

"Three satellite phones, on top of cellphones, have been in use since last October to bring more live and direct news out of North Korea," its head Kim Seong-Min told AFP.

The three satellite phone operators are based in the capital Pyongyang and the southwest, Kim added.

He said they helped spread reports last week that Pak Nam-Ki, a top financial official, had been executed for a failed currency revaluation.

Yonhap news agency said Pak was shot dead in Pyongyang in an apparent attempt to quell public anger about the bungled revaluation. South Korean officials have said they could not confirm the report.

The North strictly bans the use of unauthorised cellphones or satphones.

Another Seoul-based rights group, Open Radio for North Korea, has reported that a North Korean was executed in late January for using a Chinese cellphone to tell a defector friend in South Korea about hardships there.

Rights groups say authorities operate cars with special equipment to detect unauthorised cellphone signals along the border with China.

"It would be harder for authorities to detect our satellite phone users, but we ask our correspondents to employ extra caution given the huge risk of being caught," said Kim.

He said possession or use of satphones could lead to a charge of espionage punishable by death.

The North has a legal mobile phone service, mainly for Pyongyang residents who register as users. The use of unauthorised phones is banned as part of a crackdown on information from outside the country.