The attack reportedly took place in the early hours of last Friday and the suspect, who police have not named, was detained later that day, however police said he was not a lawmaker, The Daily Star reported.
Police said the man had been released on bail until January pending further inquiries.
A spokesman for the House of Commons, one of Britain's most recognizable buildings on the banks of the River Thames in Westminster, said they were aware of the incident and parliament was working closely with police, Guardian reported.
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