CN Rail lifted its lockout of more than 300 workers Wednesday after federal back-to-work legislation received royal assent.

CN said it invited workers to return to their jobs as of 7 p.m. ET Wednesday night. The employees are expected to be back at work as early as Thursday, which would end a week of rotating strikes.

Reports said the United Transportation Union was instructing its members to return to their jobs.

The House of Commons passed a bill Tuesday night to force an end to the dispute. Ottawa said the economy was threatened because the two sides appeared to be unable to resolve their differences. The legislation takes effect Thursday night.

"We cannot let this situation go on," Labour Minister Jean-Pierre Blackburn said. "We simply cannot allow the parties to jeopardize our economy."

It's the first time the federal government has used back-to-work legislation to end a labour dispute in eight years.   

The UTU, which represents 2,800 yard workers and conductors, said it would continue to press for better working conditions for its members.

"This bill appears to be intended to pave the way for CN Rail to attack our rights," UTU vice-president John Armstrong said in a statement released after the vote.

Regional deals targeted

"They want to break up our bargaining unit in order to weaken the workers' ability to stop management from pushing older workers out of the way and manipulating work rules and schedules at workers' expense."

The railway announced two days ago it would try to pursue regional contracts with its employees, saying it could not reach a nationwide settlement because of union infighting. The union said it would file an unfair labour practice charge.

Rotating strikes began April 10 after union members rejected a tentative deal reached to end a 15-day strike in February.

CN then locked out hundreds of workers who participated in the rotating strikes.

The strike in February prompted many industries to complain of serious problems in shipping or receiving material. CN management was able to keep many trains running, but could not maintain full service.   

Major industrial users of the rail freight system welcomed news of back-to-work legislation.

"Canada's forest products industry has yet to recover from the impact of last February's strike, and this latest walkout has resulted in significant service disruptions, lost contracts and penalties for our members," said Avrim Lazar, chief executive of the Forest Products Association of Canada.

Statistics Canada said the February work stoppage contributed to a decline of more than $900 million in Canada's trade surplus that month as exporters struggled to ship goods to the United States.

With files from the Canadian Press