ALBANY – Assembly Democrats are putting conditions on giving their approval for the expansion of Manhattan’s Javits Convention Center, including a formal review under New York City’s land-use laws.

Legislation introduced yesterday by the Assembly speaker, Sheldon Silver of Manhattan, also separates the project more explicitly from a proposed football stadium on the West Side, gives a stronger preference to unionized labor for the construction work, and diminishes the governor’s control over the Javits Center’s board.

Assembly officials portrayed their Javits proposal as a less controversial alternative to Governor Pataki’s bill, introduced in early June.

Business and labor officials immediately objected to the provision subjecting the project to the city’s Uniform Land Use Review Procedure. Projects sponsored by the state government, which owns the convention center, are usually exempt from this process, which takes several months.

“We appreciate that they’re trying to separate out Javits – for which there is a consensus in support – from the more controversial elements of the West Side plan,” said the president of the Partnership for New York City, Kathryn Wylde. “On the other hand … they have included in the bill items that could both delay Javits and set a precedent that may be a problem.”

The president of the Building and Construction Trades Council of Greater New York, Edward Malloy, praised the labor-friendly provisions of the Assembly bill, but expressed concerns about the land-use review.

This process “may unnecessarily de lay a project that nearly all New Yorkers agree must advance as soon as possible,” Mr. Malloy said in a statement.

Officials at City Hall also questioned the need for additional public review, saying such requirements would be “counterproductive.”

A co-sponsor of the Assembly bill, Richard Brodsky of Westchester County, predicted the review would move quickly because the Javits project has broad public support.

“There ought to be a way for the democratic process to be involved in this,” he said. “The more people who are participating in these things, the better.”

A spokeswoman for Mr. Pataki, Lynn Rasic, said the administration is reviewing the Assembly proposal. “We hope this is not another obstructionist ploy by the Assembly leadership,” she said in a swipe at Mr. Silver.

The $1.4 billion Javits project is a central part of Mayor Bloomberg’s plan for redeveloping the West Side. It calls for expanding the convention center by almost 50%, to 1.1 million square feet, and adding a 1,500-room hotel. It would be financed with a mix of private and public money, including a new $1.50-anight hotel tax.

Critics have warned that the larger center could become a costly white elephant, but proponents insist the expansion is necessary for Javits to compete for convention business.

At its present size, “we’re turning away business, and that is basically shooting ourselves in the foot in terms of our economic development strategy,” Ms. Wylde said.

The Bloomberg administration has linked the project to plans for a $1.4 billion stadium that would provide extra space for convention events, host home games of the Jets football team, and, possibly, serve as a venue for the 2012 Olympic games. The stadium proposal has run into stiff opposition from West Side neighborhood groups and the owners of Madison Square Garden.

“The key here is breaking the stadium out,” Mr. Brodsky said. “That should break the logjam.”