Workers building a road in the village of Miaohe, Zigui county, just upstream of the dam, reportedly set off a blast that triggered a landslide, which brought the tower down.

Too much explosive had been packed into the blast, which was set just 10 metres from the tower, the newspaper said. The unexpectedly powerful explosion on Jan. 5 dislodged 20 cubic metres of rock, which knocked the tower over and then buried it.

The tower had carried the 110-kilovolt Lian-Guan line, which links Liantuo in Yiling district and Guanyingge in Zigui county and normally supplies power to a large area on both sides of the river.

The blackout has affected parts of Zigui, Xingshan and Badong counties, as well as the Shengnongjia forest district, the newspaper reported, but it did not say if the power outage has had any impact on the dam site itself.

It could take at least a month to complete the necessary repairs and restore power to the affected area, officials in Yichang, near the dam site, were quoted as saying.

The accident, which was reported by the Anhui newspaper on January 9, does not appear to have been covered by any other Chinese media outlet.