Electronic jamming signals from North Korea have been affecting scores of civilian flights in and out of South Korea but did not endanger the aircraft, a Seoul official said Wednesday.

"We've confirmed the GPS [global positioning system] jamming signals have been stemming from the North," Lee Kyung Woo, a deputy director at the state Korea Communications Commission, told AFP.

The transport ministry, in a statement and comments to AFP, confirmed the jamming but did not say who was responsible.

The North has been accused before by Seoul of jamming GPS systems but there was no previous widespread effect on civilian flights.

A ministry statement said 241 flights by South Korean airlines and 11 operated by nine foreign airlines had been affected since last Saturday. It said Seoul that day issued a warning notice for pilots and airlines.

Kim Choon Oh, a ministry director, said GPS disruption was noticeable around Incheon airport, the South's main international airport.

"Authorities are tracing the origin," he told AFP.

"Despite disruption in GPS, there is no serious threat to the safety of flights because planes are using other navigation devices."

Kim said there was a brief disruption to the GPS systems of civilian flights last year, "but this kind of widespread disruption is unusual."

North Korea in recent weeks has frequently threatened offensive action against the South. It accuses its leaders of disrespect during Pyongyang's celebrations last month of the centenary of the birth of founding leader Kim Il Sung.