Riot police were deployed on the streets of Glasgow after violence flared following an Irish unity march.
Mounted officers, a police helicopter and dog units were tasked to the city’s Govan area after protesters against the march sparked a riot, and witnesses said smoke bombs were used.
Police said the planned march through the city's Govan area, organised by the James Connolly Republican Flute Band, was met by hundreds of "disruptive" loyalist counter demonstrators at about 7pm on Friday.
The force said this led to "significant disorder" around Govan Road, which was blocked by officers.
Chief Superintendent Mark Hargreaves said: "Police Scotland has a duty to facilitate processions and any peaceful protest, but this kind of behaviour by persons demonstrating against the parade is utterly unacceptable.
"It is extremely disappointing to see people acting in this fashion, causing fear and alarm to members of the public as well as putting many people at risk."
He added: "Police Scotland will undertake a thorough and robust enquiry, and take any necessary action against those found to have been causing disruption."
Glasgow City Council advised of the road block in a traffic bulletin, and Govan Subway Station also closed due to the incident but has since reopened.
Once the road reopened at about 9.45pm, a few police vehicles remained in the area, including riot vans.
Debris and what appeared to be makeshift barriers could be seen at the side of the road.
Glasgow City Council said the incident was ”unacceptable" and described those involved in the violence as “morons”.
It said: "The council is clear that the law expects it to facilitate public processions; including those that some people oppose or find offensive.
"However, this cannot continue to be at the expense of the overwhelming majority of Glasgwegians, who want nothing to do with these marches, or counter-protests.
"The city needs and wants fewer marches. We are prepared to consider any action that will protect communities from morons intent on bringing mayhem to the streets of our city.”