Global tech giants Google, Apple, and Microsoft are "under review" by the Australian Tax Office (ATO), senior executives said on Wednesday, as politicians grilled them about corporate tax avoidance.

The review means the tax office has not renewed agreements with the companies on transfer pricing, an accounting practice blamed for helping large companies minimise their tax bills, the executives told a Senate hearing in Sydney.

Developed nations are trying to crack down on tax loopholes that allow multinational companies to shift their profits from high tax countries to more relaxed regimes.

Australia is following the lead of Britain and the United States in holding a public inquiry into corporate tax avoidance, although the company executives declined to provide full details about their financial structures.

Google Australia's Managing Director Maile Carnegie, Apple's Australia and New Zealand head Tony King and Microsoft tax executive Bill Sample all declined to say what proportion of their income was taxed in Australia and how much of it they moved overseas, if at all.

"It's pretty alarming that some of you would come to an inquiry like this without basic information about where the revenue is going and where the Australian sales are going," said Sam Dastyari, the Senate Inquiry's chair.

All thee executives denied though that they avoided tax.

"We haven't shifted any profits," said Apple's King.

Carnegie and Sample told the inquiry that they booked most of the revenue from their Australian business in Singapore, while King said Apple Australia booked its revenues and sales locally.

In their submissions to the Senate committee, both Google and Apple called for Australia to participate in the 'base erosion and profit shifting' plan that was discussed at the meeting of the Group of 20 countries in Australia last year.

The G20 has agreed to develop stricter rules on cross-border taxation to close loopholes that have allowed companies such as Starbucks Corp, Google, and Apple to avoid paying taxes.

Those providing evidence to the inquiry later this week include mining giants BHP Billiton and Rio Tinto, as well as corporate regulators.