UEFA has confirmed Rangers face disciplinary action over alleged discriminatory chanting.
The club's fans have been reported for chants during their Europa League last-16 first-leg tie against PSV Eindhoven on March 10. A UEFA spokesman said: "There is a disciplinary case open against Rangers. It will be discussed on April 28 by the control and disciplinary committee in Nyon."
Rangers vowed to defend themselves "vigorously" against the UEFA charge as they claim they have been unfairly singled out.
In a statement on the club's official website, Rangers chief executive Martin Bain said: "We are utterly dismayed to be informed by UEFA that it is to take disciplinary action against the club. We will defend the club's position vigorously at the hearing which is scheduled for later this month.
"UEFA has already made clear in previous disciplinary hearings that sanctions against Rangers have been mitigated by the extensive work the club does to tackle sectarianism.
"A high-ranking UEFA delegation also described our club as exemplars of best practice in this area and only a few weeks ago the First Minister complimented us on the efforts we make as a club.
"Our position regarding sectarian and offensive singing has been made clear time and again - we condemn it and those who indulge in it only damage the interests of the club.
"We have worked closely with our supporters groups to try to deal with this issue and believe that few other clubs make as big an effort to tackle anti-social behaviour.
"We are not saying there is not a problem but we are saying that for many years now we have made strenuous attempts to address it. We do, however, believe that it is absurd to think that only Rangers supporters sing offensive or sectarian songs.
"That is patently not the case and we are left to conclude that there is a disproportionate focus on Rangers. It has also become clear there are people who have been determined to undermine our club at any cost and have constantly lobbied UEFA and other organisations to take action against Rangers."
The disciplinary case is the fourth Rangers have faced at the hands of UEFA in five years.
They were fined almost £18,000 in November 2009 after their fans clashed with Romanian police during a Champions League match against Unirea Urziceni. Two years earlier, the club were fined £8,280 on an improper conduct charge for fans' behaviour at an away UEFA Cup game against Osasuna.
The Scottish champions were fined £13,300 for supporters' discriminatory chanting and £9,000 following an attack on their opponents' team bus during an away game against Villarreal in 2006.
Rangers avoided sanctions over the trouble that followed their UEFA Cup final defeat against Zenit St Petersburg in May 2008 because it took place away from the stadium.