Sonoma County manufacturers next year could cut the duty fees they pay on imported components and other goods as part of an expanded foreign trade zone linked to the Port of San Francisco.

The port announced Friday that it has asked the federal government to expand the Bay Area trade zone to include portions of Sonoma, as well as Napa, Marin, Solano and Contra Costa counties.

While the formal application process could take six months, customs officials provided key backing last month by agreeing to allow county companies as far north as Healdsburg to be included in the zone, said Jim Maloney, the port's maritime marketing manager.

In such zones, companies pay no duties or quota charges on items they import and later export. For domestic sales, the duties on those imports can be deferred or lowered.

News of the proposed trade zone expansion drew applause Friday morning in Santa Rosa at the economic conference sponsored by the county Economic Development Board. The board had urged the port to include Sonoma County within the trade zone.

County Supervisor Mike McGuire told the audience that the trade zone will mean more local jobs.

Ben Stone, head of the Economic Development Board, said the trade zone can attract companies that use imports in their manufacturing process.

"This is another incentive we can offer them," Stone said.

Dick Herman, president of 101 MFG, an alliance of manufacturing executives in Northern California, called the trade zone "potentially very significant" in a county whose exports in 2010 totaled $1.1 billion.

"It supports doing the high value-added manufacturing here in the United States, and that's what we want," he said.