British and Irish Lions head coach Warren Gatland has urged the players' union to help resolve the 'Brexit-style' deadlock between the Lions and Premiership Rugby.

As it stands, English-based players are not allowed to play in the warm-up Test against Japan next June.

Gatland says this could cost players in a "50-50 selection call".

"The Brexit negotiations are still going on, and it's the same thing with us," Gatland told BBC Sport.

"We hope that we can come to some agreement with Premiership Rugby in terms of the release of those players.

"And maybe it's the players' association [who get involved], and the players have a voice in terms of what they want."

The Lions' meeting with Japan falls a week before the start of the World Rugby international window, and also clashes with the 2021 Premiership final.

English clubs never release players for matches outside of the window, although it remains unclear whether players who have finished with their club commitments will be able to join up for Lions camps, regardless of whether they can play against the Blossoms.

Premiership Rugby sources have suggested players not involved in the final will be blocked not only from appearing in the match at BT Murrayfield, but also prevented from attending camps before the game - which would be a significant blow to the Lions' preparation.

"It's perfectly understandable that the players in the Premiership final play in the Premiership final, but if England have a great next six months, the numbers [of English players] could be a third, up to a half of the squad," added Gatland.

"So that does hamper your preparation.

"I can promise we will be taking the best possible squad, but if you end up with a 50-50 call, and you are not quite sure of one player over another player, and one player is available to you for two weeks of preparation and another one isn't, that may be the difference between someone getting selected and someone not getting selected.

"I really hope it doesn't happen and we can come to some agreement and get those players being made available to us, and give those players the best possible chance of preparing for what is going to be an incredibly tough tour.

"The players go off to South Africa, and if successful they come back as heroes and that creates an enormous amount of interests in the clubs. We are just hoping we can come together and find some compromise."

Gatland 'surprised' at Springboks

Meanwhile, Gatland says he is "surprised" at South Africa's decision to pull out of this year's re-shaped Rugby Championship.

The South African Rugby Union cited travel restrictions and player welfare as reasons behind their move not to play in the competition in Australia, meaning the Springboks will not play a Test through the whole of 2020.

"It could end up being 20 months between their last game and the first [Lions] Test. So they may be underdone, and it will be disappointing from my perspective because I won't get a chance maybe to see them play," Gatland said.

However, he sympathised with South Africa's director of rugby Rassie Erasmus.

"Those are kind of the times we are in at the moment," Gatland said. "I can understand from Rassie's point of view, they hadn't had a lot of domestic rugby, so they felt they were going down to Australia being undercooked and understandably not wanting to expose themselves.

"They talked about an injury risk, I am not too sure that was the case, but that's their prerogative and they felt they needed more rugby.

"But what they are going to do - internally or externally - ahead of the Lions, I am not too sure, so it is a bit of a wait and see."