The NHL is ready to move to Phase 2 of its plan to return to play, and will soon allow players to train in small groups at team facilities, according to a memo circulated to teams over the weekend.

The NHL didn't put an exact date on when Phase 2 will go into effect, though it said it was targeting early June. In the memo, the league said it will continue to "monitor developments in each of the club's markets, and may adjust the overall timing if appropriate."

Phase 1 involved self-quarantine for players and hockey staff and began on March 12.

The new protocols would allow for a maximum of six players to train at the team facilities at once. On-ice sessions are for players only, with no coaches or other team personnel allowed on the ice. Players must wear face coverings at all times, except when they are exercising or on the ice.

The NHL stressed that participation in Phase 2 is "strictly voluntary" and teams should not require players to return to their playing city yet. On March 16, players were told they could travel anywhere; last week, commissioner Gary Bettman revealed that 17 percent of players were currently outside North America.

Phase 2 is a crucial step for the NHL as it aims to complete the 2019-20 season and award a Stanley Cup this summer. On Friday, the NHLPA's executive board approved the format the NHL can use if it returns to play. Twenty- four teams would make the field -- including the Montreal Canadiens and Chicago Blackhawks, who were both sellers at the trade deadline. The top four teams would get byes.

There are still plenty of details to work out, including whether the teams will be reseeded after the first round.

The NHL is aiming to stage games in two or four "hub cities," which will be in existing NHL markets. The NHL has narrowed its list down to eight or nine options. Las Vegas is a heavy favorite, given the NHL's strong relationship with the city and its ability to potentially house as many as 12 teams in one hotel. League sources say the NHL would also like to choose a Canadian city as a host for a variety of reasons -- one of which is that it is cheaper to stage games in Canada.