April 19 (Reuters) - Canadian copper miner Teck Resources said on Wednesday Swiss commodities giant Glencore Plc "opportunistic" proposal has not changed, and continued to recommend that shareholders vote for a planned spin-off.
Earlier in the day, Glencore told Teck shareholders it was willing to improve its $22.5 billion takeover offer.
In a letter to shareholders, Teck said Glencore is seeking to frustrate the vote and pre-empt a competitive future landscape, which is good for Glencore, and bad for Teck's shareholders.
(Reporting by Mrinalika Roy)
