MONTREAL - SNC-Lavalin says its executive vice-president of hydrocarbons and chemicals has resigned, a little more than a year after joining the engineering and construction giant.

The company announced after markets closed that Calgary-based Andy Mackintosh has resigned effective immediately after accepting a position with another undisclosed company.

Mackintosh's hiring was lauded when it was announced by former CEO Pierre Duhaime in August 2011.

"While we are sorry to see Andy go, we respect his reasons, and wish him much success in his career," stated SNC-Lavalin president and CEO Bob Card.

Card took over in October, several months after Duhaime was "relieved" of his duties after an independent review conducted by the company discovered he signed off on $56-million worth of payments to undisclosed agents, breaching the company's code of ethics. His departure was classified as a retirement.

Duhaime had said he expected the appointment of Mackintosh would allow the chemical and petroleum division to reach its ambitions of being a global player by being much more aggressive. The division accounted for 15 per cent of SNC-Lavalin's revenues last year.

Duhaime and former senior executive Riadh Ben Aissa were charged last week with conspiracy to commit fraud and utter false documents in connection with a contract pertaining to the multibillion-dollar McGill University Health Centre.

The infractions are alleged to have taken place between April 30, 2009, and Aug. 31, 2011.

SNC-Lavalin spokeswoman Leslie Quinton said Mackintosh left voluntarily and for personal reasons.

"His departure has nothing to do with last week's news," she said in an email.

Ric Sorbo, senior vice-president and general manager of the business unit has been appointed acting head of the business unit until a replacement is appointed.

Before joining SNC-Lavalin, Mackintosh was executive general manager for Asia and North America with Australian industrial company Transfield Services, where he oversaw major contracts such as Suncor, Shell Canada and Canadian Natural Resources.

A citizen of Australia, he has more than 25 years of experience in the oil and gas industry. He graduated from the University of Aberdeen in Scotland with a master of science in project management.

SNC-Lavalin is one of the leading engineering and construction groups in the world, working in some 100 countries.

On the Toronto Stock Exchange, SNC's shares closed down $1.02, or 2.65 per cent, to $37.48 in Tuesday trading.