Jan 28 (Reuters) – The chief executive of Osisko Mining Corp said Tuesday he has not spoken to anyone at Goldcorp Inc since shortly before Goldcorp announced last week it would make an unsolicited takeover bid for the mid-tier Canadian gold producer.

Osisko CEO Sean Roosen, who described the bid as “very hostile,” said he got a courtesy call about the offer roughly half an hour before Goldcorp, one of the world’s biggest gold miners, sent out a press release announcing it.

Roosen spoke to media on the sidelines of a conference in Toronto, where he urged investors to reject the offer. Osisko has called the 15 percent premium being offered by Goldcorp “very low.”

“We are five minutes into the first game of a seven-game series. Don’t sell your stock,” said Roosen in a lunchtime presentation at the TD Securities Mining Conference.

Vancouver-based Goldcorp, which wants control of Osisko’s Malartic gold mine in Quebec, said last week it went ahead with an unsolicited offer after a long series of frustrated attempts to engage Osisko in talks.

Roosen said he expects portfolio managers will make sure they are rewarded for the risk they took investing in Osisko before it had a producing mine. Malartic, Osisko’s only mine, reached commercial production in the spring of 2011.

“If you’re going to invest in growth assets and they’re going to trade at a zero premium at the end of the day, that doesn’t really make a business model for portfolio managers,” he said.