Relatives of World Trade Center victims upset by plans to move this year’s September 11 commemoration away from ground zero have reached a deal with Mayor Bloomberg that will allow them to mourn at the site where their loved ones perished, the mayor’s office said. Mr. Bloomberg said he met with the families yesterday and agreed to their proposal that they be allowed to descend briefly into the seven-story pit that was the trade center’s basement to pay their respects.

The city had announced last month that the sixth anniversary ceremony could not be held at the 16-acre trade center site, as it had been each year since the 2001 attacks, because the construction going on there made the area too dangerous for such a large gathering.

But Mr. Bloomberg said yesterday that the families’ proposal for “a very limited and controlled level of access” to the pit had been deemed safe by the Port Authority of New York and New Jersey, which owns the lower Manhattan site.

“We will work with the Port Authority to allow family members to safely descend the ramp in a single file stream that keeps moving into a limited area below grade to pay respects and to then ascend back to street level,” he said in a statement.

The main memorial ceremony will be held, as originally planned by the city, at a plaza off the southeast corner of the site, Mr. Bloomberg said. The families had objected that the park was too small.

Some relatives of those who died had been alarmed that there was to be no access to what they view as hallowed ground. Every year on previous anniversaries, thousands who lost loved ones have gone to the site for the reading of the victims’ names and to lay flowers in the pit.