When it comes to blocking ads, though, disgruntled consumers do not have to rely on their Internet service providers. Consumers already have the option of downloading software like Adblock Plus to do the job for them.

Free is the second-largest Internet access provider in France, behind Orange, which is operated by France Telecom and has 9.8 million Internet customers. Because Free seeks to be a low-cost competitor, the company may feel itself particularly vulnerable to the expense of providing capacity to meet Internet users’ ever-growing demand for streaming and downloading videos, music and the like.

Ms. Pellerin, the digital economy minister, expressed sympathy for Free’s position in an interview with Le Figaro, published Saturday. “There are today real questions about the sharing of value between the content providers — notably in video, which uses a lot of bandwidth — and the operators,” she said.

“In France, and in Europe,” Ms. Pellerin added, “we have to find more consensual ways of integrating the giants of the Internet into national ecosystems.” And in a subsequent Twitter message, she said she was “no fan of intrusive advertising, but favorable to a solution of no opt-out by default.”

Google, which is currently engaged in delicate antitrust negotiations with the European Union, has been largely silent about the Free episode, appearing content to let other aggrieved parties take the lead. Al Verney, a Google spokesman in Brussels, said Sunday, “We are aware of Free’s actions and are investigating the impact.” He declined to comment further.

Free’s ad-blocking campaign began last week when it rolled out a new generation of hardware and software that enables users to block Web advertising. Free has set the ad-blocking software as the default option.

Numerama, a news site, thundered in an editorial that the move “demonstrates the power that Internet service providers can have on the content of Web sites, and the risk it represents to democracy.” Free, it said, “penalizes thousands of sites that can only make it through online ads,” including Numerama itself. Affected sites can either “join in a game of cat and mouse with Free to escape the filter,” it said, or “change their business models.”