Vancouver-based Aurizon, which supports what it says is a superior offer by Hecla Mining, will oppose the Alamos application, the company said Tuesday.
Alamos already owns a 16 per cent stake in Aurizon and contends the sole purpose of the plan is to block its hostile takeover offer.
Alamos said an earlier rights plan was meant to give the board time to find an alternative offer, but the new plan is different.
"The Aurizon board continues to attempt to prevent Aurizon shareholders from deciding for themselves where they see greater value," said Alamos chief executive John McCluskey.
Aurizon enacted the second shareholder rights plan after signing a friendly deal that would see Hecla Mining take over the company under an agreement valued at $796 million in stock and cash.
Hecla's offer, valued at $4.75 per Aurizon share (TSX:ARZ) when it was announced, is 10 cents more than the Alamos Gold bid, valued at $4.65 per share when it was announced.
Apart from a nominally higher total value, the $513.6-million maximum cash component offer from Hecla is almost $210 million above the cash cap in the Alamos stock and cash bid.
However, the Hecla offer requires approvals from two-thirds of votes cast at a shareholder meeting and Alamos has said it will try to get sufficient support to kill the deal.
Meanwhile, McCluskey said Aurizon also overstepped its duties when it put in place a $27.2-million break fee in connection with the proposed Hecla deal.
"The board knew Alamos owned 16.1 per cent of Aurizon's shares and knew that we had received strong support from other large shareholders making it unlikely for the Hecla transaction to proceed," he said.
Aurizon said Monday it erected the new defence to ensure all shareholders would have an opportunity to choose the Hecla offer. It warned Alamos could block the Hecla deal even if more than half of its shareholders supported the deal.
Aurizon has eight properties in Quebec, including the Casa Berardi gold mine, as well as several development and exploration projects.
Alamos, which has its head office in Toronto, has a mine and mineral rights in Mexico and an advanced development project in Turkey, while Hecla has mines in Alaska and Idaho, as well as projects in the U.S. and Mexico.
Aurizon shares were unchanged at $4.51 Tuesday afternoon on the Toronto Stock Exchange, while Alamos shares were up 14 cents at $14.70.