A man suffered a fractured skull in an alleged assault at the Walkabout bar in Carlisle early yesterday morning.
Cumbria Police are appealing for information.
In a statement today a police spokesman said the attack on the 27-year-old happened at 1.30am on Monday.
The suspect, a 31-year-old Carlisle man, has been released under investigation.
Call Cumbria Police on 101 if you can help the investigation, asking for DC 2328 Gibson.
Alternatively, call Crimestoppers anonymously on 0800 555 111.
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