The former head of construction for Canadian engineering firm SNC-Lavalin has been arrested in Switzerland, where he is being held on accusations of corrupting a public official, fraud and money laundering tied to his dealings in North Africa.

Justice officials in the Swiss city of Bern confirm that since mid-April they have been holding former SNC-Lavalin executive vice-president Riadh Ben Aissa.

Ben Aissa is the subject of a probe into his business dealings in North Africa, including his native Tunisia and Libya, where he helped SNC-Lavalin win billions of dollars in projects from the Gadhafi regime, according to a joint investigation by CBC-Radio Canada and Switzerland’s public broadcaster RTS.

"The federal prosecutor's office confirms the arrest of a dual Tunisian-Canadian citizen," said Jeannette Balmer of Switzerland’s Ministère Public de la Confédération (federal prosecutor’s office) in an interview with CBC/RTS in Bern, Switzerland.

"He is a former vice-president of the SNC-Lavalin group. He held this position until February of this year."

The arrest was made in connection with a criminal probe that the department opened last year, in May 2011, and involves "suspicion of corrupt practices, fraud and money laundering in connection with dealings conducted in North Africa,” Balmer said.

Swiss authorities refused to specify which countries are involved.

Swiss investigators behind raid on SNC-Lavalin

Swiss officials say they are the ones who requested the RCMP to conduct a search of SNC-Lavalin’s Montreal headquarters on April 13, in which thousands of documents were seized and a dozen executives were questioned.

Asked about the RCMP raid, RCMP Sgt. Marc Menard said the RCMP acknowledges that it received a request for assistance from the Swiss, but cannot answer questions or comment on specific details of an ongoing investigation. He also said the force cannot comment on the arrest.

CBC News has also confirmed that the RCMP commercial crimes section is conducting a probe into Ben Aissa and former SNC-Lavalin VP controller Stéphane Roy, who were forced to resign from the company in February.

The pair oversaw operations in Tunisia and Libya and sparked controversy among employees inside the firm over their close dealings with Saadi Gadhafi, who directed numerous construction contracts to SNC-Lavalin, including a controversial prison.

The company in March announced it was contacting the RCMP after internal audits discovered $56 million in improper payments under Ben Aissa's watch.

The two were also responsible for hiring Canadian mediator and consultant Cyndy Vanier, who is currently in prison in Chetumal, Mexico, accused of helping organize a plot to smuggle Saadi Gadhafi and his family out of Libya to Mexico under assumed identities.

Vanier told CBC News in a recent prison interview that the RCMP visited her in March to speak to her "as a witness" as they asked about her contracts and dealings with Ben Aissa and Roy. The RCMP has refused to discuss the case publicly.

CBC News was first tipped off about Ben Aissa's arrest in Switzerland in mid-April, but until now officials and Ben Aissa’s lawyers were unwilling to confirm it.

"We decided not to issue any comment on the situation," said Ben Aissa’s Montreal-based public relations spokesman Frederic Lepage on April 18, when first asked by CBC News about Ben Aissa's detention.

Nor would Lepage offer any comment into the RCMP search of SNC-Lavalin’s headquarters and their probe of $56 million in improper payments under Ben Aissa’s watch.

Asked Sunday about the Swiss allegations, Lepage and Ben Aissa's Montreal lawyer Emmanuel Laurin-Légaré offered no comment.

SNC-Lavalin in recent months has issued statements distancing itself from Ben Aissa, indicating his resignation in February related to the company's "code of conduct." Ben Aissa has denied that and threatened the company with legal action over its description of his departure.

The company has also claimed that Ben Aissa and Roy’s hiring of Cyndy Vanier last summer and fall was "unauthorized" by the firm, despite bank records obtained by CBC News from Vanier that show wire transfers of more than $1 million last August and September from SNC-Lavalin into a “retainer account” set up by Vanier Consulting, which Vanier insists was being used for a legitimate contract.

Vanier says the work involved chartering private aircraft to assist in what she believed was an "employee reintegration plan" in preparation for transporting company workers back into Libya once the conflict there ended.

SNC-Lavalin's CEO Pierre Duhaime also announced his surprise retirement in late March, just as the company announced in a public news release that auditors conducting an internal review discovered $56 million in improper payments, some of which were made by Ben Aissa and secretly approved by Duhaime, despite refusals and proper permissions by SNC-Lavalin's chief financial officer.

SNC-Lavalin said Sunday it has not been informed of any details in the case against Ben Aissa.

"SNC-Lavalin is committed to co-operating fully with any authorities who request its assistance in resolving the issues in which it is affected," company spokesperson Leslie Quinton said in an email to CBC News.

When asked why Duhaime in late March was allowed to retire while remaining on the pay roll until late June and enjoying a $4.9-million severance package amid the questions raised by the company's own audit, SNC-Lavalin's Leslie Quinton would only say the company has "previously explained our position regarding Mr. Duhaime's departure."

"We remain committed to resolving issues surrounding the misallocated payments and voluntarily turned our internal investigations results to the authorities," Quinton wrote.

In a separate statement released later on Sunday, Quinton added that, "If crimes have been committed by Mr. Ben Aissa or any other former employee, the company believes that they should be held accountable."

The Swiss have had an antagonistic relationship with Muammar Gadhafi's regime since 2008, when Hannibal Gadhafi, the fifth oldest of the dictator's six sons, was arrested with his wife in Geneva for assaulting their two servants. Gadhafi retaliated by throwing out Swiss diplomats, closing Swiss businesses, arresting Swiss nationals, suspending oil deliveries to Switzerland and withdrawing assets worth nearly $8 billion from Swiss banks.

Swiss officials apologized a year later to normalize relations and secure the release of two Swiss businessmen, who had been barred from leaving Libya, but Moammar Gadhafi continued his assault in early 2010 when he urged a jihad — or holy war — against the alpine country for its vote against the construction of new minarets.

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