French Interior Minister Gerard Collomb speaks during a media conference regarding security at the ministry in Paris, Thursday, Sept. 6, 2018. (AP Photo/Michel Euler)

Paris - French President Emmanuel Macron was left scrambling to fill another key cabinet post Wednesday after Interior Minister Gerard Collomb resigned, the third minister to step down in two months.

Prime Minister Edouard Philippe took temporary control of the top portfolio while Macron began searching for a replacement for 71-year-old Collomb, previously one of the president's most loyal allies.

The departure of Collomb, nicknamed "France's top cop" because his ministry is in charge of security and immigration, has thrown the government into flux.

Macron initially refused his resignation Monday but gave in late Tuesday to Collomb's request to be allowed to quit to campaign for his former job as mayor of the city of Lyon.

He had previously announced plans to step down next spring, but critics complained his priorities had already turned to campaigning for his old fiefdom and pressured him to quit immediately.

The Liberation newspaper described the back-and-forth as "extraordinary dilly-dallying which seems more like something from a music-hall than government politics".

Collomb's replacement will be appointed "within a few days", according to government spokesman Benjamin Griveaux.

At Wednesday's regular cabinet meeting, Macron slammed opposition and press comments suggesting the resignation amounted to a "crisis", Griveaux told reporters.

"Nothing that has been happening in the past 48 hours is tantamount to a political crisis," he said. "The government is fully at work."

Collomb's exit adds to the woes of 40-year-old centrist Macron, who is battling record low approval ratings after 17 months in power.

It comes just weeks after popular environment minister Nicolas Hulot resigned live on radio without warning Macron, saying he felt "all alone" in the government on green issues.

- 'Father and son' -

Collomb, a former Socialist and political heavyweight, had previously compared his relationship with Macron to that of a father and son, and wept during the new president's inauguration in May 2017.

But their relationship is reported to have soured this summer over a scandal surrounding Macron's former security aide Alexandre Benalla.

Benalla was caught on camera roughing up protesters at an anti-government demonstration while wearing a police helmet.

The affair blew up into a major scandal after it emerged that Macron's office knew about the incident but kept Benalla on staff, only firing him after Le Monde newspaper broke the story.

Summoned to appear before a parliamentary inquiry, Collomb had pointed blame at Macron's office, saying it was up to the presidency to report Benalla to prosecutors.

- 'Firing line' -

Collomb "did not appreciate being put in the firing line over an affair which he didn't believe was anything to do with him", an aide said.

The rift between him and Macron appeared to deepen in recent weeks, with Collomb saying last month that the government "lacked humility" -- echoing accusations of arrogance often levelled at Macron personally.

Collomb served as Lyon mayor for 16 years until Macron tapped him for the interior ministry, and it had long been rumoured that he was eyeing a fourth term at the helm of France's third-biggest city.

He is the third minister to quit Macron's government since August, following Hulot and former sports minister Laura Flessel.

The search for a new interior minister -- one of the most powerful jobs in France -- comes as Macron wrestles with problems on multiple fronts in his second year in office.

The former investment banker came to power at the head of a new centrist party promising to clean up politics and revive France's sputtering economy.

But his government has been forced to cut growth forecasts to a lacklustre 1.6% this year as his pro-business reforms struggle to jumpstart an economic turnaround.

His ratings have also tumbled, with most polls showing around 30% approval.