New York City said Wednesday it is fielding complaints that Verizon Communications Inc. has used stalling tactics to block competitors’ high-speed Internet service, the latest salvo in an ongoing dispute.

The announcement comes a week after the city said Verizon hadn’t fulfilled a pledge to deliver fiber-optic connections for television and high-speed Internet to anyone who wants them.

The new allegations focus on the pipes snaking under New York’s streets, which are supposed to be open to any independent Internet provider to lay its own fiber-optic cables. City officials say Verizon is being accused of hampering rivals’ access to those conduits.

“We are disturbed by reports that the company and its subsidiary, Empire City Subway, may have engaged in practices that hamper access to key infrastructure by other operators,” said Anne Roest, commissioner for the Department of Information Technology and Telecommunications.

Through its acquisition of Empire City, Verizon controls the piping, or conduit, that is used by to telecom providers in New York City.

Problems gaining access to infrastructure are a common complaint in the telecom business, where capital costs are high and expenses can be prohibitive.

Optical Communications Group Inc. President Brad Ickes has said his company faced higher costs, especially in Brooklyn, Queens and Staten Island, after Verizon changed the rules for how to access infrastructure around 2006. Those rules made it harder for telecom companies to use their own workers to inspect the manholes and pipes running under city streets, Mr. Ickes said. Instead, competitors must pay Verizon technicians to check the infrastructure for them.

Verizon spokesman Rich Young said the company charges fair prices for inspections that are already regulated by either the city or New York state’s Public Service Commission, depending on the borough.

“If a company that does business, with us or Empire City, has a complaint, it should be brought directly to us,” he said, adding that the city was targeting the carrier as it starts contract negotiations with its employees’ main labor union.

“It’s very convenient to raise these allegations two days after the negotiations with the union began,” he said.

A city official said the complaints were unrelated to the carrier’s union talks.

Last week, the city released an audit conducted by the Department of Information Technology and Telecommunications that found Verizon had failed to live up to terms in a 2008 agreement that said it would deploy its fiber network FiOS to anyone in the city who wants it. The audit found more than 40,000 requests for service pending, about three-quarters of which were outstanding for 12 months of longer.

Verizon says it has held up its end of the deal. The primary reason many buildings still don’t have service, the company said, is because it is struggling to get access from landlords.

Mayor Bill de Blasio has made expanding broadband access a priority. In 2013 while working as the city’s public advocate, he criticized Verizon for what its apparently slow progress building out FiOS particularly in neighborhoods in many of the city’s poorer areas, such as Upper Manhattan and the South Bronx.