Rangers say they have received numerous reports from fans and staff regarding issues at Porto’s stadium during the Europa League defeat and will be “pursuing them with the relevant parties”.
Rangers will collect further information about the complaints, with reports suggesting visiting fans were held inside Estadio do Dragao for up to two hours after the 3-1 defeat.
Djeidi Gassama gave Danny Rohl’s team the lead but the home side fought back to win and leave Rangers in 32nd place of the 36 teams in the Europa League phase.
A Rangers statement read: “Following the match in Porto, we’ve received multiple reports from supporters and staff about issues in and around the stadium.
“That’s not what anyone who travelled to support Rangers should have had to deal with, and we share the concern, anger and frustration felt by those affected.
“We will be gathering complaints and feedback and will pursue this with the relevant parties.”