'Whereas a few years ago ICC was willing to accept a window for the IPL, now the question is: do we need windows for Test cricket?'
Mike Brearley and Brendon McCullum warned of "a looming potential crisis" in international cricket and stated the game could soon reach a "point of no return" as it struggles to compete with T20 leagues across the world.
Former England captain Brearley, in his final meeting as chairman of the Marylebone Cricket Club's World Cricket Committee, warned that players "from countries lacking the funds to pay their top players well" will see those players "choose these domestic tournaments ahead of making themselves available for their countries."
They led calls for a "rethinking of the distribution model in international cricket", besides urging the International Cricket Council to build on their "conceptual plans" for a Test Match Championship.
"For international cricket to flourish, competitive levels need to be close and teams need to be able to field their best players. The committee is worried that with the spread of privately owned T20 leagues and the rapid increase in remuneration, more players from counties lacking the funds to pay their top players well will choose these domestic tournaments ahead of making themselves available for their countries," Brearley was quoted as saying by ESPNCricinfo.
"The more this happens, the greater the threat to international cricket, not only to Test cricket, but also to ODI and T20s.
"The committee is aware of the gradual encroachment of domestic T20 leagues into cricket's schedule and the threat this poses to Test cricket. Whereas a few years ago ICC was willing to accept a window for the IPL, now the question is: do we need windows for Test cricket?"
Former New Zealand skipper Brendon McCullum, who also sits on the committee, said the absence of AB de Villiers from the South Africa side for the Test series against England is "another red-flag moment" for Test cricket and warned of a "tipping point" for the game as a whole.
"I don't see T20 leagues as the devil, by any stretch," McCullum said.
"But it's how we continue to make sure Test cricket continues as an important game at the same time. That's where there's probably a tipping point: what's more important? These leagues or the international game?
"The actual health of the game is outstanding but the perception in some parts of the world is that the entertainment of Test cricket is diminishing. So we're trying to ensure there is context to every Test and we feel the Test Championship would bring that in and we encourage the ICC to continue to bring this to the table."
Brearley termed de Villiers' absence a "wake-up call".
The MCC World Cricket committee has, over recent years, argued for a revision of the sport's laws which have largely been incorporated into the ICC Playing Regulations.
