Broadband provider CenturyLink has joined the list of ISPs and trade groups suing the U.S. Federal Communications Commission over its net neutrality rules.

CenturyLink filed its lawsuit Friday, becoming the seventh organization to challenge the rules approved by the FCC in late February. The FCC officially published the rules in the Federal Register, the official publication for U.S. agency rules, earlier this week, prompting a round of lawsuits.

The company objected to the FCC's reclassification of broadband from a lightly regulated information service to a more heavily regulated common-carrier service. CenturyLink spends hundreds of millions of dollars a year to "build, maintain and update an open Internet network and does not block or degrade lawful content," it said in a statement.

The common-carrier regulations, dating back to the 1930s, "not only have no place in the 21st century economy, but will chill innovation and investment," the company added.

The FCC is confident it will prevail in the lawsuits, Chairman Tom Wheeler said Friday.

CenturyLink, based in Monroe, Louisiana, is the third-largest telecom carrier in the U.S. It acquired Qwest in 2011, and it has about 5 million broadband customers, with its presence the strongest in the U.S. South, Mountain West and parts of the Midwest.

The six other lawsuits come from two ISPs -- AT&T and Alamo Broadband -- and trade groups CTIA, the United States Telecom Association (USTelecom), the National Cable and Telecommunications Association and the American Cable Association. Alamo and USTelecom filed lawsuits in late March, with the trade group refiling its suit on Monday. AT&T and the three other trade groups filed lawsuits on Tuesday.

The new net neutrality rules, approved by the FCC on Feb. 26, would prohibit broadband and mobile carriers from selectively blocking or slowing Web traffic. The rules reclassify broadband as a regulated telecom service, instead of treating it as a lightly regulated information service, as the FCC has done for the past decade.

Grant Gross covers technology and telecom policy in the U.S. government for The IDG News Service. Follow Grant on Twitter at GrantGross. Grant's email address is grant_gross@idg.com.