Argentina’s president Cristina Fernández de Kirchner will write letters to the US actor Mia Farrow and former tennis superstar Martina Navratilova in response to tweets by the two celebrities about the mysterious death of a federal prosecutor who accused Fernández of covering up the country’s worse terror attack.

The case of Alberto Nisman – who was found dead just days after accusing Fernández of covering up Iran’s involvement in a Buenos Aires bomb attack that killed 85 people – has gripped Argentina, and drawn widespread media coverage around the world.

Investigators have yet to determine if Nisman’s death was murder or suicide, and the case has also prompted fervid speculation over the possible culprits.

“Looks like Argentina’s Prez not only covered up 1994 bombing of a Jewish center, but also killed the prosecutor,” Farrow wrote on Tuesday, with a link to a New York Times story on the case.

A deleted tweet by Mia Farrow Photograph: Twitter screengrab

She later deleted the tweet but retweeted two more tweets on the case, with links to another other articles on the case.

Last month, former tennis champion Navratilova tweeted a link to a New York Times article, adding: “And this all stinks.”



Argentine President Now Says Prosecutor’s Death Was Not a Suicide, via @nytimes- and this all stinks... http://t.co/IrQWmfWJV1 — Martina Navratilova (@Martina) January 23, 2015



The next day she posted a second tweet on the subject linking a Huffington Post article, with the comment: “Terrible what is going on in Argentina”.



Both stars received an avalanche of replies from supporters and opponents of Argentina’s president – and prompted Fernández to write her own reply to the two celebrities.

“The Argentinian state and the president will send two letters with the corresponding explanation regarding the situation in the case,” cabinet chief Jorge Capitanich told reporters on Thursday.

“Media manipulation is noticeable with a unilateral strategy tending to discredit the government,”Capitanich said.

Fernández, currently on a state visit to China, is facing growing indignation at home over Nisman’s death, and her response to the brewing political crisis. The president at first described the death as a suicide, but later suggested he may have been murdered by rogue elements in Argentina’s intelligence service to discredit her.

Official reaction to the death has exacerbated the perception that the government had failed to provide clarity in the case.

When the opposition newspaper Clarin reported that Nisman had drafted an arrest warrant for Fernández, Capitanich issued an angry denial, tearing up a copy of the newspaper to pieces on live television – only for the chief investigator in the case to admit days later that the report was true.

On Wednesday, presidential secretary Aníbal Fernández, not a relative to the president but one of her most trusted advisers, fired a series of tweets at Farrow saying she was basing her views on “misinformation”. He sent Farrow links to Fernández’s own writings on the Nisman case.

“Perhaps more info, our history in UN and CFK efforts as congresswoman will soften @MiaFarrow’s harsh words towards a remarkable world leader, who along with late husband and former Prez Nestor Kirchner have embraced justice, human rights & equality their entire lives” he tweeted.

A protest march to the building of Congress marking one month from Nisman’s death has been set for 18 February. Leading opposition politicians have said they will attend. Legislator Patricia Bullrich of the PRO party yesterday called on her followers to join the planned “silent march” demanding justice in the case.