SAN FRANCISCO �” A team representing the U.S. Olympic Committee scrutinized San Francisco’s proposal for hosting the 2016 Summer Games on Thursday, questioning whether the city has appropriate venues for track and field events and the opening and closing ceremonies, among other issues.

Although the San Francisco 49ers last month unveiled a plan for a new stadium at Candlestick Point that would have enough seats to host a major event such as the Olympics, Mayor Gavin Newsom said the USOC representatives expressed concern whether the facility and other sites in the city’s bid would be finished in time.

“Eighty-three percent is not 100 percent of venues already completed,” he said, adding that the city would provide alternative options to the still-to-be built 49ers stadium when it submits an updated proposal to the USOC next month. “There is a growing feeling that NFL stadiums are not the best opening and closing venues.”

The USOC team �” composed of Bob Ctvrtlik, the committee’s vice president for international relations and two technical consultants �” offered a similar critique on Wednesday when it visited Chicago, another of the three finalists vying to be America’s entry in the international competition to host the 2016 Olympics.

Chicago officials have floated the idea of using both the 61,500-seat Soldier Field and a nearby temporary stadium for the opening and closing ceremonies. The USOC team is scheduled to meet with officials in Los Angeles, which hosted the 1984 Olympics, on Friday.

Ctvrtlik would not provide specifics of his meeting with Newsom and other backers of the city’s bid, saying only the detailed feedback he and the consultants provided was designed “to help them craft a bid that maximizes their strengths and to minimize some of the shortcomings.”

“We were not in the business of coming to flatter the cities. That is not in their, nor the US Olympic Committee or our country’s best interest,” he said. “It was a very concrete, open discussion, and we were critical in many areas. But the criticism was aimed, as it was in Chicago and as it will be in Los Angeles, at strengthening these bids.”

Newsom said that if he and the group working on San Francisco’s bid decide they can’t realistically meet the USOC’s expectations in terms of time and infrastructure, he would take the city out of the running before the committee picks a finalist, a decision expected by March.

“Either the city can or cannot perform,” he said. “We want to make sure they have confidence in us and we have confidence in the process, ... whether we can deliver on their expectations. And there is a chance we might not be able to do that.”

Besides the stadium issue, USOC members questioned the adequacy of the Bay Area’s transportation system and whether the Golden Gate Bridge and other significant landmarks made the region especially susceptible to a terrorist attack, Newsom said.

Scott Givens, managing director of the committee overseeing San Francisco’s bid to host the 2016 games, said that after sitting through the three-hour meeting he was “supremely confident we can answer the questions of the USOC and present a very good case for the San Francisco Bay area.”

“What’s nice about the Bay Area is there are so many great venues, it’s real easy for us to take that feedback and modify our plan,” Givens said.

The International Olympic Committee is expected to choose a site for the 2016 Games in 2009.

The US last hosted a Summer Games in 1996 in Atlanta.