The Metropolitan Police confirmed the discovery during a routine search of the Commons chamber on Wednesday.
“Enquiries have led officers to believe that the phone was purposely placed in a location with the aim of causing disruption to business in the House. An investigation has been launched and enquiries are ongoing. We have updated the Speaker and Clerk of the House”, a statement from the Met Police said.
A spokesperson for UK Parliament said: “While investigations continue, we have decided to temporarily limit full public tours in both Chambers from Saturday 6 September, until further notice. Public access to the rest of Parliament is unaffected and remains open as usual.
“We have robust and proactive security measures in place in Parliament and the safety and security of everyone who works or visits here remains our top priority.”
All UK residents are entitled to a free guided tour of the Palace of Westminster, which can be booked by contacting their local MP.
Guided tours and self-guided audio tours are also available to all visitors, including tourists.