PARIS (Reuters) - The French Senate referred President Emmanuel Macron’s top aides to prosecutors on Thursday for withholding information from an investigation into Macron’s former bodyguard, prompting the government to accuse the legislature of exceeding its powers.

French President Emmanuel Macron arrives for a European Union leaders summit in Brussels, Belgium March 21, 2019. REUTERS/Toby Melville

In one of the sharpest confrontations in years between France’s powerful executive and its parliament, Macron’s government described the move by the opposition-controlled Senate as a “political coup”.

The Senate announced on Thursday it had referred Macron’s top aide Alexis Kohler, his chief of staff Patrick Strzoda and Lionel Lavergne, the Elysee’s top security official, to prosecutors.

It accused them of withholding information from an investigation into former presidential bodyguard Alexandre Benalla, who was sacked last year after being filmed beating up protesters while wearing a police helmet and civilian clothes.

“This is neither reasonable nor measured, this is a political coup,” government spokesman Benjamin Griveaux told reporters of the Senate move.

Prime Minister Edouard Philippe took the rare step of boycotting the government’s weekly question-and-answer session at the Senate, his office said.

The Senate has been investigating Benalla, who was fired as Macron’s security aide after video emerged of his confrontation with May Day protesters.

He was sacked only after Le Monde newspaper broke the story, prompting criticism that the president had failed to act sooner. He has also been investigated over other accusations, including that he used a diplomatic passport after he was fired.

Last month, an investigative committee of French senators said the top Elysee officials had withheld information from them during their six month investigation and recommended the case be referred to prosecutors.

Macron’s government has argued that the Senate was contravening the separation of powers by questioning decisions by the executive branch. Many experts on French constitutional law say the Senate has acted within its rights.

“This is a perfectly legitimate move by the senate’s investigative committee,” Jean-Philippe Derosier, a constitutional law expert at the University of Lille told Reuters, saying the government’s criticism was “not justified.”