Oaktree Capital Management LP, the largest shareholder of Tembec Inc (TMB.TO), said on Friday it would vote against Rayonier Advanced Materials Inc's (RYAM.N) US$807-million acquisition of the Canadian forest products company.

Los Angeles-based Oaktree, which owns 19.9 per cent of Tembec, called on Rayonier to sweeten its bid, saying: "If the offer is not increased, we believe Tembec shareholders would be better off ... independent."

Jacksonville, Florida-based Rayonier, which supplies cellulose found in cellphones, computer screens and pharmaceutical drugs, said in May it would buy Tembec to expand into packaging and forest products.

It offered $4.05 in cash or 0.2302 of a Rayonier share for each Tembec share.

In a separate statement on Friday, Tembec said proxy advisory firm Institutional Shareholder Services had recommended that the Canadian firm's shareholders vote in favour of the deal under Rayonier's proposed terms.