Veraison, an activist shareholder group in Aryzta, said the company's decision to delay holding its EGM until September shows it is "disrespecting the trust and fundamental rights of shareholders".
In a statement, Swiss group Veraison said the EGM, which it had requested on May 20, will now not take place until September 16 - four months after the request was made.
Earlier this week, Irish-Swiss food group Aryzta said it was delaying its proposed extraordinary shareholders meeting after receiving unsolicited takeover approaches by investors.
"The proposed timing is primarily intended to provide an opportunity to allow the strategic review process in which certain third parties have expressed an unsolicited interest in acquiring the company's entire issued share capital to be sufficiently advanced to enable the board of directors to frame an appropriate recommendation with the advice of its financial advisers," it said.
Board members Dan Flinter and Rolf Watter will resign after the EGM, while Gary McGann indicated that he will step down as chairman then unless the company has announced a significant transaction for shareholder consideration.
The maker of McDonald's burger buns and Cuisine de France bread, has been struggling with debts after a failed acquisition spree.
Veraison said today that since 2017, Aryzta's board of directors has failed to set the right strategic course to focus the company and reduce the complexity of Aryzta.
"The massive value destruction is a clear reflection of this," it added.
"It is disconcerting that the strategic review announced at short notice in May 2020 by the board of directors of Aryzta has apparently failed to reach any conclusions," the shareholder group said.
"Rather, the sale of the company is now the apparent priority. This leads to unneeded confusion among employees, customers, suppliers, and other stakeholders. Apparently, the Chairman and the board do not believe in the company's future under their leadership," it added.
Veraison said it is "convinced" that Aryzta's shares trade at a significant discount to their intrinsic value.
"In our view, the company operates in fundamentally attractive markets, with strong positions in its core markets," it said, adding that Aryzta has a strong potential if the company "takes the right path".
"The proposed leadership change has over recent weeks received strong support from many other shareholders and is in the best interest of all stakeholders," it stated.