NFL players are not expected to return to their team facilities until training camp, sources told ESPN.

Most teams already have reopened their facilities on a limited basis for essential employees amid the coronavirus pandemic, but healthy players still are not allowed to return.

Discussions about when to allow players to return are ongoing, sources said, and neither the NFL nor any teams have announced official dates for when training camp will begin.

NFL commissioner Roger Goodell informed teams Tuesday, in a memo obtained by ESPN, that they must hold training camps at their main practice facilities because of the virus.

The memo also said that teams will not be allowed to hold joint training camp practices with other teams.

Goodell cited limiting travel, exposure and contact along with eliminating the need to clean and maintain two facilities in the league's decisions, which he noted that the "NFLPA was strongly in favor of."

"These steps are being taken for the 2020 preseason to address the current conditions and are not expected to be in place in 2021," Goodell said.

Ten teams practiced away from their main practice facilities last year.