Some News Corporation shareholders have demanded to know why the media giant made million-dollar contributions to pro-Republican campaigns in the US midterm election campaign.

At News Corporation's annual general meeting in New York, company chairman Rupert Murdoch had to defend his decision to make the donations.

Only 50 shareholders showed up for the AGM, which is normally a tightly controlled affair.

But the News Corporation chairman appeared uncomfortable as he was taken to task by some shareholders for approving a million-dollar donation to the Republican Governors Association and another million dollars to the US Chamber of Commerce, which is paying for thousands of pro-Republican ads.

Mr Murdoch was grilled about an interview he gave where he said it was based on a personal friendship with a former Republican congressman, which he conceded in the meeting was a foolish throwaway remark.

Lead independent director Sir Rod Eddington said he understood the concerns of shareholders and call for transparency and promised a review.

But shareholder Lance Lindblom worries about the damage to the company's news brands.

"The corporation needs to go deeper into saying, 'in our considered judgement these were of value to shareholders'," he said.

"I think they need to give us a rationale."

Mr Murdoch told the AGM that some change is needed in Washington and is in the interests of America and all News shareholders.

He says some money was also given to Democrats.

The 79-year-old also told the gathering he intends to stay on as chairman as long as he is healthy.