More than 2,000 Tunisians marched in the country’s capital protesting a proposed amnesty bill that would see businessmen accused of corruption under overthrown president Zine El Abidine Ben Ali walk free.

At the demonstration against the Economic Reconciliation bill on Saturday, protesters claimed the bill would contradict the spirit of Tunisia's 2011 revolution that overthrew Ben Ali.

But government officials said a pardon would be a way for the businessmen to inject their fraudulent money back into the country's economy.

Waving flags and banners that read "No to forgiveness" and "Enough Corruption", the protesters, accompanied by opposition party leaders and activists, marched through Tunis' central avenue.

"Today we are saying the defenders of the revolution are still here," protester Sabra Chrifa told Reuters news agency, wearing a t-shirt with the slogan "No Forgiveness".

"We can't accept something that whitewashes corruption like this."

The controversial bill would allow the accused businessmen to reveal stolen money and repay the amount without fear of prosecution.

There are no exact figures but initial estimates say approximately $3bn could find their way into the legally taxed economy.

The draft bill was proposed by Tunisia's President Beji Caid Essebsi, a former Ben Ali official. But it has been stuck in Parliament for the past two years.

For many critics, the law is simply an amnesty for criminals and a way to rehabilitate Ben Ali's allies back into Tunisian society.

"We're here to say to Essebsi and his cohorts that the law will fall in the street like in all democracies," Popular Front opposition leader Ammar Amroussia said.

"He wants to pass this corrupt law, but these protests show that we say no."

The proposal is now being debated in committee and will then go to a plenary session.

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On Wednesday, Essebsi had defended the bill while criticising calls for protest, saying that the legislation aimed to "improve the investment climate" in the country.

These protests, as well as others in the south of Tunisia this month over jobs, come at a sensitive time for Prime Minister Youssef Chahed who is struggling to pass austerity measures and public spending reforms to help economic growth.

Since the 2011 revolution, Tunisia's democracy has advanced with free elections and a new constitution. Yet the government has faced growing social discontent over the economy, especially in inland regions.

Unemployment in Tunisia stands at around 15 percent according to official figures.