HALIFAX -- Power companies in New Brunswick and Nova Scotia said they were doing everything possible to restore electricity Thursday as thousands of Maritimers entered their sixth day of darkness since post-tropical storm Arthur hit.

NB Power spokeswoman Meghan Gerrish said some outages could drag into next week and the utility was reaching out to customers who could be among the last to be reconnected. The utility had said it was aiming to have everyone back online by the weekend.

"In a lot of cases we have to rebuild the infrastructure," Garrett said. "The damage is just extraordinary."

The City of Fredericton said more than 4,000 trees were damaged or downed by the storm, not including trees on private property or in city parks.

Gerrish said NB Power has spent more on tree-trimming this year than ever before and continues to learn from a December ice storm that cut power to more than 600,000 customers in New Brunswick, southern Ontario and Quebec.

In Nova Scotia, some residents expressed frustration with the length of time it is taking to get the lights back on.

Bilynda Whiting, a resident of Kingston whose power remained out when she went to work Thursday morning, said she was fed up with the situation.

"We pay them a lot of money," said Whiting, 47. "It's unacceptable. ... It just proves that this infrastructure is very fragile."

Nova Scotia Power president Bob Hanf said Wednesday the company has made improvements since hurricane Juan pummelled the region in 2003. He said $74 million has been spent in the last four years to strengthen the utility's systems, on top of the $60 million it spends annually.

But Hanf also apologized for problems the utility had communicating estimated restoration times to its customers through its website and call centre.

Provincial Energy Minister Andrew Younger said his department will review the utility's response to the storm.

"If there is one group of customers who didn't experience a reasonable restoration time given the conditions in that area, then that's not acceptable," he said Thursday.

Younger said the review will also look at cutbacks to Nova Scotia Power's vegetation management program, staffing levels and current infrastructure.

"If you talk to the premier, he'll tell you that not far from his house, there's a whole line of power poles that are snapped right off that actually had nothing to do with trees hitting them. They just snapped."

The province's Opposition Progressive Conservatives have also asked the Utility and Review Board to review what they said were Nova Scotia Power's "failures to provide service in the aftermath of this storm, specifically analyzing the failures of the company to communicate to Nova Scotians."

The board said it is premature to say whether it will conduct a review but it is within its mandate to do so.

Utilities in both Nova Scotia and New Brunswick said they will conduct reviews of their own once all power is restored.

Electricity consultant and researcher Tom Adams said he believes Nova Scotians, who pay among the highest power rates in the country, are right to question whether they're getting good service for their money.

But he said it's too soon to say what went wrong in either province.

"I would not jump to the conclusion that there's an infrastructure deficit nor that there's necessarily a maintenance deficiency," he said from Toronto.

As of 4 p.m. Thursday, about 29,000 customers were without power in New Brunswick, more than half of whom were in the Fredericton area. About 3,900 were still in the dark in Nova Scotia.

Post-tropical storm Arthur swept through the region Saturday, knocking down trees and power lines.