Uruguay's foreign minister resigned abruptly Wednesday, after the release of recordings in which he allegedly seeks to cover up information involving Sebastian Marset, an accused cocaine trafficker and subject of an international manhunt.

"Things are not as they have been presented," the ex-diplomat Francisco Bustillo claimed in a statement obtained by AFP.

He nonetheless said the situation was "sufficiently sensitive" that he offered his immediate resignation to President Luis Lacalle Pou, who is currently in the United States.

Bustillo's decision followed testimony Wednesday morning by former deputy foreign minister Carolina Ache, as part of an investigation into the circumstances around Marset's ability to receive an Uruguayan passport.

Marset is wanted on drug charges in his native Uruguay, Paraguay, Brazil and the United States.

Authorities accuse him of being one of the most powerful drug traffickers in the Southern Cone region, transporting multiton shipments of cocaine through Uruguay.

He was the subject of a massive search effort in Bolivia in late July, with thousands of officers deployed to hunt him down, but was apparently able to evade capture.

In late 2021, he was detained in the United Arab Emirates on charges of using forged documents, but managed to ultimately receive an authentic Uruguayan passport.

- 'Lose your phone' -

Ache resigned in December 2022 amid a scandal over the dissemination of a WhatsApp chat from November 2021, in which an Interior Ministry official described Marset as "a very dangerous and weighty narco."

Ache told reporters that she had testified Wednesday "to collaborate with the investigation so that once and for all the facts are clarified and the whole truth is known."

The WhatsApp message contradicted Bustillo, who, when testifying before the Senate in August 2022, had said that "In November (of 2021), who among all of us knew who Marset was?"

Ache reiterated Wednesday that she had no involvement or interference in the processing of Marset's passport, but said she warned the issuing office "that it was someone dangerous" as soon as she was told.

"What I realized later is that everyone already knew what it was about long before I did," she told a press conference Wednesday, without providing details of her testimony.

Later in the day, audio recordings of telephone conversations and chat messages that she had presented as evidence were published and confirmed by several media outlets.

"Lose your phone," Bustillo recommends to Ache in one of the calls, which according to the outlet Busqueda was recorded on November 14, 2022.

In another clip, Bustillo calls the interior ministry official who messaged Ache a "moron," noting that if he were to disclose the chats "he would shoot himself in the foot."

In his resignation statement, Bustillo denies any illegality in the processing of Marset's passport.

"Of course, neither did I lie or deviate from the truth in the parliamentary questioning," he said, accusing Ache of taking "conversations out of context and acting in bad faith."

He is set to give testimony to investigators on Friday and promised to "shed light on the veracity of what has been done and on the distorted account that has been given."