The man, who is in his 20s and is from the town, was arrested yesterday and admitted using words or carrying out behaviour likely to stir up racial hatred. He was subsequently cautioned for the offence and released from police custody.
The action follows a number of complaints from members of the public concerning allegedly racist or offensive posts on the social media site.
Two other men previously arrested over the allegations are currently on police bail. Another two men were also spoken to earlier this week about comments they had made and both agreed to remove their posts from Facebook and not to add any further comments.
Policing commander for Shropshire, Superintendent James Tozer, said: “West Mercia Police takes all reports of racism extremely seriously and a full investigation into these complaints is now underway.
“With regards to this particular issue, there has been a local prayer room in Shrewsbury for the last ten years and its users are a welcome and well established part of our community.
“We are working closely with them and other community groups to prevent any escalation of this situation.”
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