Qiagen, a fast-growing Dutch manufacturer of genetics research products, has tentatively selected a site in Germantown to build its North American research and manufacturing headquarters with a staff of 200, according to Maryland and Montgomery County officials.

The company said it has not made a final decision between the Germantown location and several other possible sites. Maryland and Montgomery County officials are prepared to offer Qiagen significant financial incentives, but the amounts have not been settled.

And some regulatory issues remain. Montgomery County Executive Douglas M. Duncan has requested a definitional change in zoning there to accommodate construction plans at the site on Route 118 west of Germantown.

"We're quite excited about opportunities in Montgomery County, but we have to make sure options are available if things don't work out as planned," Qiagen's chief financial officer, Peer M. Schatz, said in an interview.

Qiagen manufactures products and tools used in genetics-based research and diagnostics and has been seeking a U.S. site where it could be alongside leading bioscience companies, including those engaged in mapping the human genetic code, Schatz said. Montgomery County meets that requirement, he added.

State and county officials expressed confidence that Maryland will soon be chosen.

"It looks very, very positive. The level of detail they're working on suggests this is very close to a win," said Richard "Mike" Lewin, Maryland secretary of business and economic development.

One unknown in the equation is the reaction of Germantown residents, some of whom have heard about a possible major corporate location to their town and are worried about it, officials said.

Michael W. Burgett, Qiagen's vice president for North American operations, met last night with Germantown residents and business owners to review the company's plans. The meeting went well, he said.

"It's a good thing they're talking to the community. I'd hope residents would be very supportive," Duncan said. "One of the things were trying to do is get more jobs into the Germantown area to lessen the commute for residents.

"We were impressed by the level of cooperation that Qiagen received from Maryland and Montgomery County," Burgett said. "This is a significant project for Qiagen."

It would be a significant one for Maryland's bioscience industry, as well, which now employs more than 15,000 workers, an increase of more than 5 percent over the past year.

Although Montgomery County and Maryland have been centers of biotech research for many years, clustered around the National Institutes of Health, its companies have been slow to move from laboratory to full-scale production. That is starting to change, at least for the industry's leaders.

MedImmune Inc. of Gaithersburg has opened a 90,000-square-foot manufacturing plant in Frederick and is awaiting final regulatory approval to begin shipping products. Human Genome Sciences Inc. in Rockville has completed an 80,000-square-foot plant near its headquarters and has a 40,000-square-foot addition underway.

The Qiagen plant in Germantown would be larger than either, at 150,000 square feet.

The company, which has a major production facility in Germany, had sales of $136.5 million over the most recent four quarters.

It recently formed a partnership with Becton Dickinson and Co. of Franklin Lakes, N.J., to produce diagnostic testing products. Becton Dickinson has a major location in Sparks, Md., outside Baltimore, and there could be valuable links between the Sparks facility and the Qiagen plant, if it is built in Germantown, Schatz said.