MILLINOCKET, Maine — The Katahdin Avenue paper mill, which was due to cease production today, will stay open until at least the middle of next week and could return to a biomass-fueled plant as early as April 2009, union officials said Monday.

Katahdin Paper Co. LLC officials announced Aug. 26 that the mill would close on or about Sept. 2 because of a lack of work orders — a point workers dispute — and the burgeoning cost of heating oil, the mill’s sole source of heat. The last orders will be finished this week.

“They are working everybody this week and we have a series of meetings next week where we will see how the shutdown process and layoffs will proceed,” United Steelworkers Local 152 President Louis Ouellette said. “Beyond next week, I don’t know.”

The union-management meetings will determine how many layoffs occur at Katahdin Paper’s East Millinocket and Millinocket mills. Earlier notices said 208 jobs would go. As many as 100 East Millinocket workers will be “bumped” by Millinocket workers with more seniority, Ouellette said.

Workers are preparing the mill to survive months of inactivity, Ouellette said.

“It will leave the mill in a state where it can be started up quickly,” said Duane Lugdon, a representative for three United Steelworkers International unions at the paper mills of East Millinocket and Millinocket. “The maintenance effort will continue here for at least two or three weeks.”

Their Labor Day predictions are based on conversations with Katahdin Paper management over the last several days, Ouellette and Lugdon said.

That could not be confirmed with mill manager Serge Sorokin and spokesman Glenn Saucier on Monday.

But based on their access, Ouellette and Lugdon said they believe an agreement to power the mill with a biomass boiler will be signed within a month. Six to eight workers will stay on-site to maintain the mill until restart.

“I guess I would term the inking [of the deal] as imminent,” Lugdon said. “I am told on good authority that if we can get it inked, quickly, the total build time here [for the boiler] is six to nine months.”

At least some union workers will help build it. “Our interest is in seeing this built over the winter when the cost of burning oil is highest, using as many of our people as can be used,” Lugdon said.

Katahdin’s parent company, Toronto-based conglomerate Brookfield Asset Management, announced May 29 that the mill’s prodigious oil use would in 60 days force an indefinite shutdown and layoff of 208 workers if an alternative energy source weren’t found.

Gov. John Baldacci intervened, the mill found energy savings and supportive customers, and the deadline was extended repeatedly. Brookfield was in talks with alternative energy providers on Aug. 26 when its officials ordered the Sept. 2 shutdown in a manner that Baldacci and the unions said was abrupt.

Since then Brookfield has stated only that it remains in talks and that its commitment to the mill depends on successful biomass negotiations.

Baldacci, whose staff is assisting the talks, and Town Manager Eugene Conlogue, who met with Sorokin and Saucier on Aug. 26, are the only officials who have spoken publicly of tentative mill plans based on direct access to top-level company officials.

Baldacci said Saturday he plans to hold Brookfield to its commitment to reopen the mill before considering other options. The company has $95 billion in assets.