Chris Ward, executive director of the Port Authority of New York and New Jersey, told a city council hearing Tuesday that the memorial plaza will be completed by Sept. 11, 2011, the New York Daily News reported. But he said that the memorial will not be completely accessible to the public until late 2012.

The 10th anniversary is expected to be a major event with guests including the U.S. president and foreign heads of state. Ward said that the memorial plaza will be available but much of the rest of the site would be off limits.

Joe Daniels, the president of the National September 11th Memorial & Museum, suggested that 2011 is still a possible deadline for the end of construction.

"It is possible to have the entire memorial finished by the 10th anniversary, but if we can't get 100 percent, we'll get as close as we possibly can," Daniels said.