After three days of delays caused by worker strikes in French Guiana, rocket firm Arianespace opted Thursday to postpone indefinitely the launch of satellites for South Korean and Brazilian clients.

At first scheduled for Tuesday, then the two following days, launch operators finally gave up and announced Thursday that the Ariane 5 rocket will remain grounded until further notice.

The launch will not be rescheduled "until the labour situation is resolved," Didier Faivre, director of Europe's Guiana Space Centre in Kourou, told local radio.

"It is up to the competent authorities and elected representatives to resolve this situation," he added.

The problems started on Monday when striking workers erected a barricade of tyres and wooden pallets at the space centre, preventing the transfer of the rocket to its launch pad.

The rocket is to deliver communications satellites for Brazil and South Korea into Earth orbit.

The strikers include workers for public energy company EDF Guyane and staff at the Kourou hospital, according to the local trade union.

They are demanding better career development opportunities, higher salaries and improved health care.

"The evolution of the situation does not permit the restart of operations," Arianespace announced on Thursday.

"The launch vehicle, with its SGDC and KOREASAT-7 satellite payloads, remain in a stand-by mode and are being maintained in fully safe conditions."

The SGDC satellite will provide strategic communications for the Brazilian government and military services, and beam broadband services across the country, helping to provide internet access to remote and underserved communities.

KOREASAT-7, owned by South Korea's KTsat, will provide a range of video and data services over Korea, the Philippines, Southeast Asia, India and Indonesia.