NEW YORK - Work on a planned museum at the World Trade Center site has ground to a halt because of a financial dispute, and there is now no possibility it will open on time next year, New York Mayor Michael Bloomberg said Thursday.

The underground museum commemorating 9/11 victims was due to open next September on the 11th anniversary of the terror attacks, a year after the opening of a memorial at the site that has already drawn one million visitors.

But in recent months, the National September 11 Memorial & Museum foundation has been fighting with the Port Authority of New York and New Jersey over who is responsible for paying millions in infrastructure costs related to the project.

The Port Authority, which owned the trade center and is building the museum, contends that the foundation owes it $300 million. The foundation says the authority actually owes it $140 million, because of delays in the project.

The dispute has been simmering, and some details of the work slowdown were reported in November, but Thursday marked the first time the mayor and other officials have acknowledged that the fight would mean the museum will not open in 2012.

"There is no chance of it being open on time. Work has basically stopped," Bloomberg said.

Gov. Andrew Cuomo said on a recent radio program that the Port Authority was "on the verge" of suing the foundation, but both the mayor and the Port Authority said Thursday that talks continue.