WASHINGTON — For the second time in a year, the FBI’s attempt to replace its 30-year-old two-way radio network could be stalled because of accusations that the bureau is skewing its bid solicitation to favor Motorola Solutions Inc., the emergency communications industry’s dominant player.

Last year, the bureau scrapped a plan to hand Illinois-based Motorola a sole-source contract worth up to $500 million, including upgrades for other law enforcement agencies, after four competing vendors filed protests.

Now the FBI has sought competitive bids for a contract limited to modernizing its own network at a cost of about $200 million, but the action is still drawing allegations of bias from Motorola’s biggest rival, Harris Corp., which has formally protested. The conflict offers the latest evidence of how difficult it will be to break one company’s market power over a multibillion-dollar business underwritten solely by taxpayers.

It also puts the FBI in an awkward spot, since the bureau sometimes is asked to investigate allegations of antitrust abuses, said an executive of RELM Wireless, a small, Florida-based radio manufacturer that protested last year’s proposed sole-source deal.

FBI officials who “are supposed to be protecting us from monopolies are playing into the hands of a company that actually has a near monopoly in the public safety radio market – Motorola,” said Tim Vitau, RELM’s vice president of sales and marketing.

Motorola Solutions has consistently captured more than 80 percent of the state and local emergency radio market and has outdistanced its rivals in the federal market as well.

The FBI’s dilemma is that it wants its agents’ radios to be able to connect with all of the thousands of law enforcement agencies nationwide. But many state and local systems use older Motorola equipment with proprietary designs that cannot interact with other manufacturers’ products, meaning that Motorola’s rivals cannot meet the bureau’s requirement.

In a protest filed late last month, Harris alleges that the FBI’s May solicitation for bids “essentially duplicates its prior failed effort to sole-source its radio equipment contract to Motorola.”

Virginia-based Harris asked that the Government Accountability Office direct the bureau to halt its procurement until the protest is reviewed.

The FBI’s new solicitation offers a five-year contract as part of a $3 billion tactical communications contract covering various agencies.