The whole of Syria has been bit by a power blackout, according to state media.

The electricity network across the war-ravaged country is down, state news agency SANA said, citing a government source.

There were no immediate reports as to what had caused the nationwide blackout.

"Electricity has been cut across all provinces and teams are trying to determine the reason for this unexpected cut," the station said.

Residents in the capital Damascus said they had been without power since 1pm local time.

Mobile internet connections from some private providers were also said to be not working.

Syria's state mobile provider said this was partially due to "part of the network unexpectedly malfunctioning".

The country has suffered several power cuts during the course of the ongoing five-year civil conflict at an estimated cost of $3.7 billion.

Five out of the 13 main power stations in Syria have been damaged in the war.

However, it is rare for the whole of Syria to be affected as it has been on Thursday.

It comes as a partial cease-fire entered its sixth day - and was said to be largely holding, according to UN Special Envoy for Syria, Staffan de Mistura, despite reported incidents in Homs, Hama, Latakia and the capital.

Some 24 civilians - including five women and six children - have been killed so far during the fragile truce, according to monitoring group.

"Compare that number to Friday, the day before the truce came into effect: 63 civilians, including 11 children, died that day alone," said Rami Abdel Rahman, head of the UK-based Syrian Observatory of Human Rights.

Downing Street said British Prime Minister David Cameron, French President Francois Hollande and German Chancellor Angela Merkel will hold a conference call with Russian President Vladimir Putin on Syria on Friday.

Peace talks are set to resume on March 9 in Geneva.

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