Downtown businesses and residents suffering through the 12th day of a power failure got more bad news Wednesday: The blackout will last another 10 weeks.

Merchants estimate they are losing $60 million a week as a result of the failure of four power cables supplying electricity to downtown Auckland, New Zealand's largest city.Two cables repaired by city utility Mercury Energy failed when tested Wednesday. It will take 10 weeks to run a new cable into the downtown area.

"I said 10 days ago it was a dark time - it is much darker now," Mercury Energy chief executive Wayne Gilbert said.

"We deeply regret this situation. There is no apology great enough, and I realize this will be absolutely devastating for our customers, as it is for us," Gilbert said.

Downtown Auckland has been almost a ghost town since last month, when cables stressed by a heat wave started to fail.

This city of 1 million people has grown for years - but growth has outstripped infrastructure. When the strained cables started breaking down, power company Mercury Energy had no backup system.

The latest news means disaster for some small businesses, Auckland Chamber of Commerce chairman Michael Barnett said

"Quite frankly, some of the owners of small ones have said they will be better to walk away from their businesses - that's the breakdown of the fabric of the central Auckland business district," Barnett said.