Mayor Bloomberg yesterday defended the right of a group of atheists to file a lawsuit to block the return of a cross made of steel beams to the World Trade Center memorial, saying the nonbelievers have rights, too.

“You’ve got to be careful in criticizing people. No. 1, they have a right to sue, and we’ll see what the judge says,” Bloomberg said on his weekly radio show on WOR yesterday morning.

“This group of atheists, they’re free in our country to not believe and not practice, and we should defend their right to do that, just as we should defend individuals’ rights to practice and to believe.”

The group, American Atheists, filed suit against the return of the steel beams that were found standing in the rubble after the 9/11 attacks.

They say the cross is a religious symbol that shouldn’t be on a project partially financed by government funds.

It was moved during the reconstruction to a location outside St. Peter’s Church, a few blocks north on Church Street, and was just recently returned to the site, where it will be a part of the museum’s collection.

The memorial is due to open on the 10th anniversary of 9/11.