After 48 hours of intense criticism and pressure -- some from his own party -- Quebec Premier Jean Charest has dramatically expanded the powers of a public inquiry into alleged corruption in the province's construction industry.

On Friday night, Charest told a Liberal party convention he will grant the inquiry the power to subpoena any witness and to compel witnesses to testify.

When he announced the inquiry Tuesday, after two years of calls for a probe, the premier had restricted the inquiry's right to subpoena witnesses and its ability to offer immunity in exchange for testimony.

At the time, Charest said he feared testimony at the public inquiry might taint evidence that could become part of a police investigation into criminal activities.

With public opinion polls and even members of his own party critical of his stand, Charest's capitulation appears to have defused an uprising among Quebec Liberals. One delegate at the convention was proposing a no-confidence vote on the leader while a group of delegates was considering a motion that would have granted more powers to the inquiry.

Headed by Madam Justice France Charbonneau of the Quebec Superior Court, the inquiry will delve into allegations of collusion and corrupt practices in the construction industry and the awarding of public contracts in Quebec.

"If, during the progress of her work, with the accumulation of evidence she will have gathered and with the intent of protecting it, Judge Charbonneau came to the conclusion that she would need constraining powers, she will be able to make a recommendation to the government and we will abide by her request," Charest said in his opening remarks to the convention.

"Tonight, I want to make it very clear that we have full confidence in the commission of inquiry, and those to whom the responsibility has been confided to conduct this work," he added. "And if they need the power to constrain witnesses and they ask for it, we will grant that power. Because we want those who are guilty to go in front of the courts."

For years Quebec has been awash in allegations of corruption linking its multi-billion-dollar construction industry to organized crime and political parties.

The allegations became a full-blown scandal in September when a report by the province's new anti-corruption task force was leaked to Quebec media outlets.

The report detailed an elaborate web of corruption that allegedly involves civil servants colluding with construction companies and helping them find loopholes in the tendering process, allowing them to charge more for public-works contracts.

The companies, allegedly tied to the Mob and criminal biker gangs, would then use some of that extra profit to pump contributions into the coffers of political parties.

With files from The Canadian Press