Antitrust law was inadequate to preserve the openness of the Internet and to allow innovation to flourish, the top U.S. communications regulator said on Thursday, defending Internet road rules adopted last year.

"Antitrust enforcement is expensive to pursue, takes a long time and kicks in only after damage is done," Federal Communications Commission Chairman Julius Genachowski told a congressional hearing.

The FCC adopted the contentious Internet order in December, banning service providers like Comcast Corp, AT&T Inc and Verizon Communications Inc from blocking traffic on their networks. The so-called net neutrality rules, that have not yet gone into effect, would still allow companies to "reasonably" manage their networks.

Republican legislators have challenged the agency's authority in regulating Internet traffic, and pushed a measure through the House last month that would overturn the order and prevent the FCC from adopting any rules related to it.

But the chances of successful congressional action against the Internet order look slim with no similar measure pending in the Senate. President Barack Obama's advisers have also recommended he veto any such resolution.

Members of the House Judiciary subcommittee that oversees competition and the Internet asserted at the hearing on Thursday that federal antitrust laws could handle net neutrality issues, without what they view as the heavy-handed regulatory approach of the FCC.

"Antitrust law provides a time-tested and predictable system for preventing providers from engaging in anticompetitive blocking or discrimination," subcommittee Chairman Bob Goodlatte said.

Genachowski told lawmakers that antitrust enforcement was not a practical solution given the fast-paced, ever changing nature of technology.

To support his argument, the FCC chairman quoted conservative Supreme Court Justice Antonin Scalia in a case that favored the FCC regulating communications issues over applying antitrust laws to this technical area.

The rules adopted by a divided FCC on December 21 in a 3-2 decision highlighted a huge divide between those who say the Internet should flourish without regulation and those who say the power of high-speed Internet providers to discriminate against competitors needs to be restrained.

FCC Commissioner Robert McDowell, who voted against the order, told the House panel that sufficient antitrust and consumer protection laws existed to prevent and cure any of the contemplated harms outlined in the order.

The best chance of overturning the Internet order probably lies in the courts, where FCC rules have been successfully challenged before.

The U.S. Court of Appeals for the District of Columbia Circuit ruled last year that the FCC lacked the authority to stop Comcast Corp from blocking bandwidth-hogging applications on its broadband network. That ruling led to December's FCC order.

Appeals earlier this year by Verizon and MetroPCS Communications Inc of the FCC order were deemed premature by the court but challenges are expected once the order is officially published.