Mexico could be plunged into “an even bloodier” era of deadly violence against the press unless its populist leader stops harassing the media, scores of top journalists have warned after an apparent attempt to assassinate one of Mexico’s best-known news anchors shocked the nation.

In an open letter, the signatories – who include professionals from major outlets including El Universal, Excélsior, Milenio and Reforma – issued a rebuke to Mexico’s media-bashing president, Andrés Manuel López Obrador.

“Almost all of the outpourings of hatred towards journalists are incubated, born and disseminated from the presidential palace,” said the declaration, which was penned in response to last Thursday’s botched gun attack on the newsreader Ciro Gómez Leyva in Mexico City.

“Our indignation over this incident, leads us to demand that President Andrés Manuel López Obrador ceases his harassment of critical journalists,” the journalists wrote in their brief but dramatic dispatch.

“Slander, which has replaced the debate of ideas, is an invitation to physical violence against journalists who are stigmatized by the president,” they added.

“If President López Obrador does not control his angry instincts towards critical journalists, the country will enter an even bloodier phase than those which other Latin American countries have previously lived through: the murder of journalists in order to destabilize the government, or killing in return for government favours,” the letter concluded.

Mexico was already one of the world’s most dangerous places for journalists when López Obrador, who many call Amlo, took power in late 2018. But conditions have deteriorated dramatically under a 69-year-old nationalist who, like Donald Trump and Brazil’s Jair Bolsonaro, is notorious for his harangues against the press.

Some believe such verbal attacks contributed to the toxic atmosphere that saw 42 journalists murdered during the first half of Amlo’s six-year term, compared with 45 during his predecessor’s entire administration.

This year at least 16 Mexican journalists have been killed, including the celebrated Tijuana photojournalist Margarito Martínez Esquivel. One month after Martínez’s murder, Amlo traveled to the northern border city only to horrify the photographer’s grieving colleagues by berating journalists he called “mercenaries”.

Jan-Albert Hootsen, the Mexico representative for the Committee to Protect Journalists, said the “highly unusual” open letter spoke to the level of shock the attack on Gómez Leyva had produced within Mexico’s media establishment.

“We are talking about a really, really, really powerful figure within the media … [and the attack] was obviously very well organized, very brazen. It is something that normally never happens. The last time a journalist of such a high public profile was killed or even attacked in such a way in Mexico City was back in the 1980s,” Hootsen said.

Amlo last week condemned the “reprehensible” assault on Gómez Leyva, who survived thanks to his bullet-proof car. But just 24 hours earlier the president had been publicly denigrating the journalist, warning Mexicans that if they listened to such people too much they risked developing brain tumours.

Hootsen said it was impossible to prove whether Amlo’s rhetoric had a direct influence on such acts of violence but hoped the latest attack would serve as a wake-up call to Mexico’s leaders.

“Mexican authorities definitely need to do something because they stood by as journalists with far less clout were attacked and killed and kidnapped and tortured,” he said.

“[This attack shows that] all journalists in Mexico can be targeted – including the most powerful ones.”