Treasurer Joe Hockey and Tax Commissioner Chris Jordan are resisting calls to reveal the names of multinational companies that are channelling billions of dollars to low-tax jurisdictions.

Transparency became a central issue of the first public hearings of the Senate committee into corporate tax avoidance on Wednesday where multinational tech companies Apple and Google conceded all their Australian revenue is taxed in Singapore.

Mr Jordan rebuffed calls to release the names of resources companies that also use "marketing hubs" in Singapore – where the company tax rate is as low as 2.5 per cent – in an apparent bid to minimise tax.

Mr Hockey personally approved the Tax Office boss's decision not to identify companies on a list, revealed by Fairfax Media on Saturday, which transferred a combined $31.4 billion to Singapore in the financial year 2012.