The 25-year-old was one of three people arrested in Liverpool in the early hours of Thursday morning.
"All three remain in custody for interview and processing and I expect a decision on charges or release will be made later tonight."
Barton missed Newcastle's game on Boxing Day due to an ankle injury and is believed to have travelled to Liverpool for a night out in the city.
According to reports in today's Daily Mail, a complaint was made by two men who said they had been attacked by Barton and his companions.
The footballer, who grew up in Huyton, Merseyside, signed for Newcastle from Manchester City this summer in a £5.8 million deal.
But his career has been dogged by controversy and accusations of violence and disciplinary problems.