Two major SABMiller shareholders came out in support of the brewer's board late on Friday, saying it was right to reject Anheuser-Busch InBev's $100 billion takeover offer.

Poland's Kulczyk Investments, the brewer's fifth-largest shareholder with a 3 percent stake, said the proposal "does not reflect SABM's standalone growth potential" and it "supports the decision of the board of SABM to reject" the proposed cash offer of 42.15 pounds per share.

"AB InBev's bid for SABMiller is welcome, as it draws attention to the company's undervaluation, but the bid is opportunistic and Aberdeen will not support the current offer," said Devan Kaloo, head of global emerging markets, equities. "AB InBev need to rethink their numbers."

Earlier on Friday, SABMiller expanded its savings target in an effort talk up its standalone growth potential as it fights its rival's unsolicited takeover bid.