Canadian Prime Minister Justin Trudeau is under new pressure after his former justice minister released documents relating to a major corruption scandal.
Jody Wilson-Raybould says government officials tried to persuade her to shield SNC-Lavalin from prosecution.
The Canadian firm is accused of bribing officials in Libya to win contracts under Muammar Gaddafi's regime, reports BBC.
Ms Wilson-Raybould has released the recording of a phone call and other materials to support her accusations.
The files, initially given to a parliamentary committee, were released publicly on Friday.
They likely to increase pressure on Mr Trudeau, who is facing a general election later this year and has struggled for weeks to contain the fallout from the controversy.
What are the allegations?
SNC-Lavalin is facing claims that former executives paid bribes to win contracts in Libya under Gaddafi, who was ousted in 2011.
The Liberal prime minister has been accused of pressuring Ms Wilson-Raybould to push for a legal favour for SNC-Lavalin that would allow it to avoid prosecution and instead face alternative penalties, such as a fine.
The affair has seen the prime minister lose two senior ministers - including Ms Wilson-Raybould, who resigned from cabinet in February - as well as Canada's top bureaucrat and a senior aide.
Mr Trudeau has denied any wrongdoing by either him or his staff.
But opinion surveys indicate that the controversy has shaken Mr Trudeau and his government's popularity months before the election, which is due in October.
What's on the tape?
The documents made public include an audio recording, lasting nearly 18 minutes, of a December phone call between Ms Wilson-Raybould and Clerk of the Privy Council Michael Wernick about the prosecution of SNC-Lavalin.
The former justice minister and attorney general said she took the "extraordinary and otherwise inappropriate step" of recording the call without Mr Wernick's knowledge because she wanted a precise account of the conversation.
She said she was concerned about what she saw as attempts to interfere in the case.
In the call, there is a lengthy back and forth between the pair, during which the senior public servant repeatedly notes that the prime minister is interested in having the firm avoid prosecution in favour of an agreement.
Mr Trudeau and his officials have said they are concerned that thousands of jobs are at risk if the engineering firm is convicted.
She pushes back, warning she felt the conversation was inappropriate and that continued communications about the matter could cross the lines of her prosecutorial independence as attorney general.
"The recording allows members of the committee to decide for themselves" about whether or not she was pressured by Mr Wernick, Ms Wilson-Raybould writes.
Mr Wernick stepped down as Canada's top civil servant this month.