The $1.4 billion expansion of the Jacob K. Javits Convention Center is moving ahead on an accelerated schedule, according to state officials, although the plan is less ambitious than some would have liked.

Last week, the Empire State Development Corporation announced it had selected British architect Richard Rogers to design the expansion. Mr. Rogers’s projects have included the Millennium Dome in London and the Pompidou Center in Paris.

The current expansion plan will extend the convention center, which now ends at 39th Street, north to 40th Street between Eleventh and Twelfth avenues. Convention space will be increased to about 1.1 million square feet from 790,000 square feet.

In December, the state Legislature approved the project, which will cost the city and state $350 million each. Last month, the state authorized $800 million in bonds, to be backed by a $1.50 a key surcharge collected by the Hotel Association of New York City. The bonds are to be issued by the end of the year.

Even after the expansion, New York’s convention space will be much less than the square footage of other major American cities. McCormick Place in Chicago, for example, will be the country’s biggest center at 2.9 million square feet after an ongoing expansion.

The Javits expansion was linked to the plan for a West Side stadium, which was rejected this summer. The retractable-roof stadium was to have also served as extra convention space.

The ESDC chairman, Charles Gargano, told The New York Sun that there is currently no available public financing to seek a more extensive expansion, but he would not rule out future development.

“As far as 3 million square feet, if we have the funds, we would go as far as we need to go. It’s just a question of money,” Mr. Gargano said. “There is no question that once we get going with construction of northern expansion, clearly in the future we have to look at southern expansion as well, depending on the demand.”

He continued, “It was a great loss for the city of New York that we were not able to get approval for the stadium.”

The president of NYC & Company, Cristyne Nicholas, was an advocate for bigger expansion plans, but she told the Sun she is delighted that any expansion plan is moving forward.

Not everyone agrees that a further expansion of convention space would be profitable. A professor at the University of Texas who studies convention centers, Heywood Sanders, said that even the current Javits expansion plan is ill-conceived.

Mr. Sanders said the national market for convention space is already oversaturated, pointing to the recent expansion of the Boston convention space, which, he said, yielded a quarter of the predicted attendance.

Mr. Stevens noted that Javits center attendance dropped to 961,000 last year from its peak of 1.4 million attendees in 1997, even with small increases in the last two years.

Ms. Nicholas said that lack of convention space was only part of the problem. She said the city needs more hotel space for convention attendees if it is to compete with other convention destinations.

“We need that immediately,” Ms. Nicholas said.

The current Javits expansion plan calls for a 1,500-room hotel that Mr. Gargano said would be privately funded.

“There is a lot of interest there right now” from the private sector, he said.