Turkish president Recep Tayyip Erdogan acknowledges supporters prior to deliver a speech at the Presidential Palace in Ankara, on April 17, 2017

President Recep Tayyip Erdogan’s lawyer has lodged a complaint against a French political scientist accusing him of inciting an assassination of the Turkish leader, the state-run news agency reported on Monday.

The allegations against the French researcher follow comments he made about the outcome of the April 16 referendum on controversial constitutional changes that will tighten the president’s grip on power.

Philippe Moreau Defarges, a researcher at the French Institute of International Relations, said all legal paths to challenge Erdogan had been shut off and that the only two options left were civil war or assassination.

The ‘Yes’ camp won just over 51 percent, a narrower-than-expected victory, but the country’s top election board last week rejected opposition calls to annul the referendum after complaints of vote-rigging.

Defarges said on French broadcaster BFM on Saturday that Erdogan’s strengthened powers would lead “only to catastrophe”.

“There will either be a civil war or another scenario… his assassination.” Huseyin Aydin, a lawyer representing Erdogan, said Defarges’ comments were not a simple expression of opinion.

The comments were “clearly instigating the crime in question,” Aydin said in a four-page complaint submitted to an Ankara prosecutor, quoted by state-run Anadolu news agency.

Critics say Erdogan has become increasingly authoritarian since becoming president in August 2014 after more than a decade as prime minister, and the number of prosecutions for insulting him has risen.

Artists, journalists and schoolchildren have all been targeted.