Speaking after Medibank managing director George Savvides was questioned by Senate Estimates, a spokeswoman for Ms Wong said it remained Labor's policy to hold onto the top insurer.

While eyebrows have been raised at the large dividends Medibank has paid to the federal government since it was converted "to profit" in 2009, the spokeswoman said the dividends had no impact on premiums.

Medibank's recent accounts showed that the insurer intends to make a special dividend to the government of $300 million this financial year, on top of a $91 million ordinary dividend.

Last year, Medibank paid $434 million in dividends to the government, including a $300 million special dividend. There was a more modest dividend of $33 million in the 2010 financial year.

Mr Savvides is quoted telling the Senate this morning that a mooted $300 million special dividend this financial year was part of changes to "restructure the capital base of the organisation to reflect a more efficient capital structure".

The Coalition's policy is to float Medibank if it wins government. Greens health spokesman Richard di Natale told BusinessDay recently that the party had "not yet settled on a view" of whether to support a sale of Medibank.

Shadow Treasurer Joe Hockey last week accused the government of "gouging" $850 million over three years from Medibank Private. "But what is of concern is that the dividends from Medibank Private exceeded their profits over the last two years," he told the House of Representatives.

Medibank has 3.8 million members, and reported record revenue for the second year running of $5.4 billion for the year to June. But profit slumped 57 per cent to $126.6 million, due to higher claims costs and a sharp fall in investment income.

Mr Savvides has consistently said that although he is aware of speculation that Medibank could be privatised, his job is to "run it the best way we can so it's business as usual."