Striking Canadian National Railway Co. workers are sporadically returning to work across the country, in defiance against their own union leaders.

Despite pleas from the United Transportation Union to maintain picket lines, some of the 2,800 striking conductors and yard workers have agreed to return to their jobs on a voluntary basis.

In Montreal, delegates from the three union locals agreed unanimously this morning to go back on call and beef up desperately needed freight train service. Quebec forest products company Tembec Inc. today echoed calls by other resource manufacturers for government intervention to end the strike.

Yesterday, Labour Minister Jean-Pierre Blackburn threatened to table back-to-work legislation this afternoon, following morning caucus meetings.

Although a new contract has not yet been reached - mediation continues today in Montreal -- the workers decided to go back on the job as both a gesture of good faith and as a show of anger against United Transportation Union leaders for removing four key negotiators from the bargaining table this week.

"All the Montreal Island workers have agreed to return to work," said Franois Galant, a spokesperson for the UTU's Montreal locals. "We are waiting for a decision by Canadian National."

Frank Wilner, a spokesperson for the U.S.-based UTU confirmed reports of workers leaving their picket lines across the country, but insisted they represented only a small proportion of strikers.

"We are hearing sporadic reports," Wilner said. "It is not a majority, it is the minority. It is chaotic right now. What we have, to some extent, is a circus sideshow going on."

In a letter to Canadian members posted today on the UTU's website, Canadian Legislative Director Tim Secord urged members to "hold the line."

"The alternative is not what you persevered through this strike for."

Wilner accused Rex Beatty, a UTU general chairperson who was stripped of his chief negotiating status this week, of convincing workers to abandon their picket lines. The UTU has accused Beatty of working with the Teamsters' union in preparation for a raid.

The Teamsters Canada Rail Conference represents CN's locomotive engineers.

"We believe they are being incited by the general chairperson [Beatty]," he said. "While they're at work the raiding can begin."

Yet earlier this week, the UTU leadership sided with CN in trying to convince the Canada Industrial Relations Board, a quasi judicial tribunal, to deem the strike illegal. The CIRB, which has authority over certain disputes pertaining to the Canada Labour Code, instead decided the strike was legal.

Wilner said two UTU vice presidents are continuing the negotiations.

"The main job is for the two vice presidents to negotiate an agreement," he said. "And that's what they're concentrating on."