Premiership Rugby chief executive Mark McCafferty has claimed that the current British and Irish Lions schedule is "not sustainable" for overworked players.
Next summer's 10-match tour of New Zealand will see the squad depart ahead of the Premiership and Pro12 finals, while also clashing with the Top 14 final in France.
McCafferty is concerned that players could face burnout if the "punishing schedule" is allowed to continue in future years, but accepts that it is too late to do anything ahead of next year's tour.
"It is going to be very difficult next year. It is a punishing schedule and I do not know why it was signed up to," he told The Observer. "Ten games over that period is a lot and there will be difficulty for players coming off that tour going into the 2017-18 Premiership. The Lions is in the mix as we move towards the season structure post-2019.
"It is a fabulous brand and an important part of the economics for the southern hemisphere. It should carry on but it is not sustainable that players can go through a club and international season, be involved in that scale of tour, and then be in shape for the following season.
"People involved in the Lions need to listen. Do you need to play that number of midweek games when the economics are driven off the back of three Tests in the main? Nothing can be done about next year but then the agreement will be up and things need to be worked out."
Warren Gatland is the strong favourite to be named as the Lions' coach when an official announcement is made early next month.
