Rio Tinto (RIO) shareholder Palliser Capital has urged the company to bid for Teck Resources (TECK) and unify its dual-listed structure and spin off its base metals operations, Reuters reported Monday, citing a letter to the board sent by Palliser.

Palliser urged Rio to challenge Teck's agreed business combination with Anglo American, the report said, citing the letter.

"Unification is not optional - it is a prerequisite for any credible strategic combination," Reuters quoted Palliser as saying in the letter.

Rio Tinto's shareholders already rejected the arguments Palliser had recommended regarding its dual listing, the miner told Reuters.

Rio Tinto, Teck, and Palliser did not immediately respond to MT Newswires' requests for comment.

Shares of Rio Tinto were down 1.1% in recent Monday premarket activity, while Teck stock was 1% lower.

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