Rangers believe they are the victims of an organised campaign after being hit with a second UEFA disciplinary charge in eight days.
The club last night confirmed the governing body had opened a case against them over alleged sectarian chanting among their fans at the Europa League game against PSV Eindhoven on March 17.
Debt-hit Rangers have been told they face a heavy fine and a two-match ban on home supporters in European competition next season.
Rangers chief executive Martin Bain was "astounded" after UEFA added the case to an identical charge over the first leg.
Bain disclosed that both charges had been prompted by evidence from the fan-led Football Against Racism in Europe organisation despite no problems being flagged up by UEFA's official delegate.
And Bain pledged the club would fight the charges "very, very vigorously".
"We have never said that sectarian singing is not a problem but this now has all the hallmarks of a deliberate and targeted campaign against the club," Bain told www.rangersfc.co.uk.
"What else are we expected to believe when UEFA officials give us favourable reports at our matches only to indict us later on the evidence of an outside unaccountable body?
"It would appear that yet again UEFA have acted on a report from the FARE organisation when their own match delegate, this time from Northern Ireland, gave us a very favourable report."
UEFA, whose disciplinary panel will discuss the club's case on April 28, have fined Rangers twice for the same offence in the last five years.
But Rangers argue they could not have done any more to fight sectarianism and last week listed the numerous programmes they have instigated to tackle the issue at a cost of several hundred thousand pounds.
They were recently involved in a summit with Celtic, police and Scottish Government officials along with Scottish Football Association chief executive Stewart Regan.
Regan vowed to continue working with Rangers and Celtic to tackle the problem.
"It's something we've recognised in Scotland," he told Sky Sports News.
"We've set up a joint working group with the police, the Government, with the clubs themselves, the football leagues and the Scottish Football Association to try and come up with practical measures which we can put in place to do something about this because it's not good for the game, and it does tarnish the image.
"I think it needs a number of measures - I don't think one party is capable of resolving this in isolation.
"It really needs the police, the stewards and the clubs themselves to be working together to try to weed out that minority who continue to participate in such chanting."