The satellites were meant to complete the Russian GLONASS satellite navigation system. But they went into a "non-targeted orbit" following their launch from the Baikonur Cosmodrome in Kazakhstan on Sunday afternoon, the Federal Space Agency reported.

"A special Board has been established to find out the cause of the contingency and to define next steps," the agency said in a public statement.

No further information was immediately available. The Russian news agency RIA-Novosti, citing unnamed officials, reported that the satellites crashed into the Pacific Ocean off Hawaii, but US military and Coast Guard said they could not confirm that report.

The satellites were launched aboard a Proton-M rocket from Baikonur about 3:25 p.m. Sunday (7:25 a.m. ET) and were slated to be fully operational in about six weeks. GLONASS is the Russian equivalent of the US Global Positioning System network, and Sunday's launch would have brought the network up to its full strength of 26 satellites.