An influential Mexican broadcast journalist whose report about the first lady's mansion caused a scandal has been sacked, sparking anger among supporters who called her firing an affront to freedom of speech.

Carmen Aristegui had been publicly feuding with her employer, MVS Radio, in recent days after two of her investigative reporters were fired by the company.

She complained about the dismissals on the air on Friday, demanding that her colleagues be reinstated and lamenting about an "authoritarian wind" in the country.

MVS said the two journalists had been fired for using the company's name without permission in their participation in MexicoLeaks, a website created by civic groups and other media outlets, to receive leaked documents showing acts of corruption.

MVS said on Sunday that it parted ways with Aristegui because she had conditioned her staying with the broadcaster on the company reinstating the two reporters.

In a statement, MVS said it could not allow one of its collaborators to "impose conditions and ultimatums on the administration".

Presidential scandal

Aristegui's investigative team revealed last year that President Enrique Pena Nieto's wife, former soap opera star Angelica Rivera, had bought a Mexico City mansion from a government contractor.

The story sparked allegations of conflict of interest, which the president denied, adding more headaches to Pena Nieto as he faced protests over the presumed massacre of 43 missing college students.

Pena Nieto's spokesman could not be reached for comment about Aristegui's sacking.

Her supporters voiced their discontent on social media, with the hashtag #InDefenseOfAristegui2 (#EndefensadeAristegui2) a top trending topic on Twitter.

"Carmen Aristegui is an essential voice in our public life. Her departure from MVS seriously damages freedom of speech in Mexico," leading historian Enrique Krauze wrote on Twitter.

The radio station's website was briefly hacked on Saturday, with a message apologising for the firing of Aristegui's two journalists.