Verizon Communications on Friday sued the Federal Communications Commission to overturn controversial net neutrality rules, saying the regulations are too stringent and go beyond the agency’s authority.

In an ironic twist, the suit comes after a separate legal challenge by Free Press this week that says the rules don’t go far enough to protect wireless customers.

The opposition to the FCC rules portends lengthy legal battles for the agency as it tries to put into effect regulatory goals for the Internet at a time when phone and cable companies are transitioning into broadband services.

In its filing at the U.S. District Court of Appeals for the District of Columbia, Verizon said the rules are illegal.

We are deeply concerned by the FCC’s assertion of broad authority to impose potentially sweeping and unneeded regulations on broadband networks and services and on the Internet itself,” said Michael E. Glover, Verizon senior vice  president and deputy general counsel.  “We believe this assertion of authority is inconsistent with the statute and will create uncertainty for the communications industry, innovators, investors and consumers.”

Verizon’s lawsuit was widely expected. The company tried in March to sue to block the FCC rules, but the same appeals court said it couldn’t because the agency hadn’t published the rules in the Federal Register.

The FCC said it will defend itself in court and argued that Web companies have benefited from rules that provide certainty their business plans won’t be disrupted by ISPs.

"We will vigorously oppose any effort to disrupt or unsettle that certainty,” said FCC spokeswoman Tammy Sun.

Internet service providers have argued that the FCC doesn’t have clear legal authority to regulate broadband Internet services. Industry experts have mixed opinions. The FCC considered, and then abandoned, a proposal to redefine broadband Internet as a telecom service, which is directly under its regulation.

After the rules were published last Friday, the lawsuit filings began.

Perhaps most surprising was the suit by Free Press, a vocal advocate of net neutrality. It said the rules were too weak because they largely do not apply to wireless Internet networks. The public interest group filed a suit earlier this week in the First Circuit Court of Appeals in Boston.

"When the FCC first proposed the Open Internet rules, they came with the understanding that there is only one Internet, no matter how people choose to reach it,” said Free Press policy director Matt Wood. “The final rules provide some basic protections for consumers, but do not deliver on the promise to preserve openness for mobile Internet access. ”