The Montreal-based company issued a news release Thursday night saying it is seeking damages against former executive vice-president Riadh Ben Aissa and former consultant Cynthia Vanier and her company Vanier Consulting Ltd.
SNC-Lavalin's news release said its court filing alleges Ben Aissa and Vanier "conspired" with the company's former vice-president Stephane Roy to use company funds without permission.
None of the statements contained in a statement of claim filed with Quebec Superior Court have been proven in court.
The company has previously accused Roy, Ben Aissa and Vanier of plotting to smuggle the son of former Libyan dictator Moammar Gadhafi to Mexico.
Vanier was recently released after 18 months in custody in Mexico, but has proclaimed her innocence and successfully appealed her arrest and detention to the Supreme Court of Mexico.
Vanier, from Mount Forest, Ont., did not immediately respond to an email asking for comment on the SNC-Lavalin lawsuit against her. The news release did not make it clear if the latest legal action is connected to the Gadhafi allegations.
The release said a Quebec court has granted SNC-Lavalin's request for a seizure of Ben Aissa's shares in the engineering giant to satisfy a portion of the damages being sought. Ben Aissa is being held by Swiss authorities on suspicion of corruption, fraud and money-laundering in North Africa.
SNC-Lavalin's release said it's basing its legal action on emails from 2011 between Roy, Ben Aissa and Vanier.
The company previously filed a claim for damages against Roy in April.
Roy and Ben Aissa's brother have also filed lawsuits against SNC-Lavalin. Roy's action alleges wrongful dismissal while Ben Aissa claims SNC-Lavalin caused him harm for using his brother as a ``scapegoat'' while protecting its interests in Libya in the face of political change.
In a statement of defence to the Roy lawsuit, SNC-Lavalin said it was justified in firing him because he and Ben Aissa acted illegally in trying to help Saadi Gadhafi and his family flee Libya without its knowledge.
"They committed serious acts, outside their normal duties and without the knowledge of their superiors, in violation of SNC-Lavalin's code of conduct and in the blatant and total disregard of the policies and controls in place,'' it said in the statement of defence filed last month.
It is seeking more than $1.8 million from Roy to cover expenses it said it later learned were paid by the company and said its reputation was irreparably damaged by Roy's actions.
Roy has never been charged, but an RCMP affidavit used to obtain a search warrant of SNC-Lavalin's headquarters named him as taking part in an alleged effort to smuggle Gadhafi and his family to Mexico.
SNC-Lavalin also alleged that Roy worked with Vanier to create fake passports and Mexican documents for the Gadhafi family.
In its legal filing, SNC referred to emails from Vanier that it said suggest the initial plan was to get Gadhafi family into Canada, before sanctions against his travel made that impossible.
It accused Ben Aissa and Roy of using new spending authority that SNC granted them by paying Vanier and a Gadhafi bodyguard $1.85 million.
SNC-Lavalin said violating a United Nations prohibition on helping Gadhafi justified terminating Roy.
The alleged attempt to spirit Gadhafi occurred in the wake of a civil war that led to the overthrow and death of his father.