MONTREAL - Air Transat and Groupe Mach clashed before the Financial Markets Tribunal Thursday, as the real estate group tries to derail the sale of the Quebec tour operator to Air Canada.

The hearing follows a complaint filed this week by Air Transat's parent company, which is demanding that the authorities stop Mach from acquiring a large block of shares that could prevent its acquisition by the largest airline in the country.

Marc Duchesne, the real estate attorney, asked the administrative court to let the shareholders decide, citing what he considered their "fundamental right ... to choose."

Air Transat strongly criticized Mach's strategy, which offers $14 per share, an 8 per cent premium over Air Canada's $13 per share proposal, calling it "abusive, misleading and coercive."

The tour operator's lawyer, Alain Riendeau, said the proposal was promoting "a false sense of uncertainty and risk" to encourage shareholders to deposit their shares against their own interests and those of other shareholders.

In June, Air Transat did not want to consider Mach's offer of $14 per share, instead turning to Air Canada's $520million-proposal.