Legal advice to Rio Tinto is that it only needs a simple majority of shareholder support for its planned $19.5 billion tie-up with Chinese state-owned Chinalco to go ahead. a source close to the transaction said on Tuesday.

Some of Rio Tinto's UK shareholders have said the deal should be put to shareholders as a special resolution, which would mean the deal would need 75 percent support to go ahead.

(Reporting by Sonali Paul)