EstLink 2, an electricity cable between Estonia and Finland, will not return to service until the end of August, according to the Estonian public broadcaster ERR.
The Estlink 2 submarine cable between Finland and Estonia has been out of use since malfunctioning in late January.
External interference has been ruled out as a potential cause of the cable glitch, according to ERR. The fault is located near the Estonian coast.
On Thursday Elering, which manages the Estonian grid, said it had confirmed the precise site of the fault but that its challenging location was prolonging repair work.
Estlink 2 was initially expected to be out of service until 31 March.
The Estlink 2 cable is one of several electricity transmission links between Finland and Estonia. The cable is about 170 kilometres long, with about 145 kilometres of it running along the seabed.
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