Two Celtic supporters groups have called on the Glasgow club to reverse their decision over Windsor Park tickets.
The club had last week announced that they would not take up their allocation, should their side clash with Linfield in Belfast on July 14.
Linfield first have to see off San Marino side La Fiorita and, should they survive that tie unscathed, they will host Brendan Rodgers' Celtic in the first leg. That game was originally scheduled for 11/12 June but was moved to Friday July 14.
Nonetheless, Celtic announced that due to "security concerns" there would be no tickets made available to their supporters.
And now the Green Brigade and the Celtic Trust have asked the club to reconsider or even for Linfield to sell tickets directly to Celtic supporters.
“The statement noted ‘safety concerns’ but it is our understanding that the PSNI does not object to Celtic fans travelling and, indeed, Linfield has publicly encouraged the board to accept our allocation and stated they are ‘more than happy’ for Celtic fans to attend the match," said the supporters groups' statement.
“We believe that the board is more concerned with protecting the brand than the welfare of the fans or the success of our team.
“It is a very sad and strange turn of events when the custodians of our own club do not want the world famous Celtic support backing the team in a ‘crucial’ away match yet the home club welcomes us with open arms.
“We call on the board to reconsider their decision, and should they fail to do so, for Linfield to sell tickets directly to Celtic supporters."
Earlier this week a leading official from the Carnlough Travel Celtic Club had appealed for Celtic supporters to 'follow the club's approach' on tickets.