Cameron Thomas, the MP for Tewkesbury, was arrested on Wednesday night by Gloucestershire Police, and interviewed before being released on bail.
The Lib Dems said on Thursday Mr Thomas has had the whip suspended pending the outcome of a police investigation.
Gloucestershire Police said on Friday: “On Wednesday (June 17), a man in his 40s from Tewkesbury was arrested on suspicion of controlling and coercive behaviour and assault.
“The man was interviewed by officers before later being released on police bail.
“Inquiries into the allegations made against him are ongoing.”
A Lib Dem spokesperson previously said: “Cameron Thomas MP has had the party whip suspended pending the outcome of a police investigation.
“We are unable to comment further while the police investigation is ongoing.”
Mr Thomas’ party membership is also understood to have been suspended.
The former RAF officer was elected in the 2024 general election.
