The Bloomberg administration is opposing a City Council proposal to lay new regulation on the construction industry, striking a rare note of legislative discord between the mayor and Council Speaker Christine Quinn.

The council and Ms. Quinn are pushing a bill that would install new rules for using explosives during excavation and demolition, bringing in new layers of city and state oversight and requiring a city inspector on site any time a contractor engages in blasting. The bill comes in response to the partial collapse in July of a retaining wall on the Upper West Side, which fell shortly after workers on the site used explosives for excavation work.

At a council hearing yesterday, the chief of fire prevention at the Fire Department, Thomas Jensen, said the legislation “reflects a fundamental misunderstanding about the use of explosives in New York City and the controls in place that govern that activity.”

The added regulations would unnecessarily strain the department and other agencies, Mr. Jensen said, while not increasing the level of safety.

The Real Estate Board of New York and the Building Trades Employers’ Association joined in the criticism of the legislation, with a vice president of the latter organization, Henry Kita, saying that portions of the bill “will provide the impetus for increases in the cost of construction.”

However, members of the council defended the bill, saying it would add a new level of safety in a dangerous industry and provide much-desired communication with the residents and businesses near blasting sites.

“This is something that very much is important as a way of improving safety,” Council Member Melissa Mark Viverito said.

Criticizing the lack of communication with businesses and residents near blasting sites, Ms. Mark Viverito pointed to the incident on the Upper West Side. “There was no level of engagement with the immediate surrounding community,” she said.