In a letter to the National Labor Relations Board, the United Food and Commercial Workers Locals 120 and 870 and Teamsters Local 70 charge that Webvan is restricting workers' rights to free speech and the right to associate.
Executives at Foster City, Calif.-based Webvan deny the allegations. They say previous attempts to organize Webvan drivers and warehouse workers have failed and that the accusations are an attempt to turn workers against the company.
"The unions are attempting to use the media to create an atmosphere of mistrust and misunderstanding," said Webvan spokesman Bud Grebey. "Our goal is to be responsive and work in a collaborative nature with our employees and to communicate openly."
The move comes as other union efforts at Internet companies have faltered, even as some dot-com employees have shown a willingness to embrace unionizing efforts.
Workers at Amazon.com and consumer electronics store Etown.com have attempted to form unions in the past year. But this week the Amazon customer service workers who were part of the unionization effort were laid off as part of larger cutbacks. At Etown, layoffs hit 13 of the 36 customer service workers who were involved in the unionization effort there.
In the Webvan case, union officials accuse the company of prohibiting workers from discussing issues, seeking support of a union, or using company e-mail to pass information about unions. Rich Hedges, spokesman for both UFCW locals, said the UFCW and Teamsters have filed charges with the NLRB on behalf of Webvan workers.
Webvan has not been contacted by the NLRB, Grebey said.
Webvan workers have already rejected the union at the company's Oakland, Calif.-based distribution facility, Grebey said. Employees understand the company is under pressure to band together to stay in business.
"We can fight together or against each other," he said. "United we survive and divided we fall."
Webvan, which has yet to make a profit and has said it could run out of operating cash sometime in the fall, is fighting to survive. Like most dot-coms, its stock has lost more than 95 percent of its value in the last year, and its share price is scraping bottom.
At the close of the markets Thursday, Webvan was trading at 47 cents a share. The low valuation has prompted the Nasdaq to warn the company that unless its stock rises above $1 sometime within the next three months, it could be removed from the stock market.
Hedges, who was handing out pro-union leaflets at Webvan's Oakland facility on Friday, predicted that Webvan workers will unionize by the end of the year. He said the unions want Webvan to survive and thrive, but not at the expense of the company's workers.
"We're not trying to harm the company," Hedges said. "We're trying to help the workers."