(Repeats story from late Wednesday)

By Joachim Dagenborg

OSLO, May 25 (Reuters) - Norway will take a first step this week towards using its $850 billion sovereign wealth fund, the world's biggest, as a tool to combat the use of tax havens, two key members of parliament's finance committee told Reuters on Wednesday.

The country's right-wing minority government will be asked to take a two-pronged approach to regulation, examining both the fund's own use of ownership structures designed to cut its liability for tax on its foreign investments as well as that of companies it invests in, the politicians said.

The move follows the Panama Papers leaks in April, which revealed details of corporate and individual tax evasion and triggered a global backlash against tax havens.

"We need to clarify the extent of the fund's exposure to tax havens," said finance committee chairman Hans Olav Syversen of the centrist opposition Christian Democrats, on which the government frequently relies for support.

"The most probable scenario is that parliament will tell the government to provide a set of tools to help ensure that tax havens, in the real sense of the word, don't find the room for manoeuvre that they've had until now," he added.

The Government Pension Fund Global, commonly known as the oil fund, invests cash from Norway's crude and natural gas production in foreign stocks, bonds and real estate to share the windfall revenues with future generations.

The finance committee is currently processing the government's annual whitepaper on the fund and is expected to publish recommendations to the full parliament on Friday.

"There will definitely be an amendment about tax havens," said Torstein Tvedt Solberg of Labour, the largest opposition party. "As shareholders we don't want companies to conduct negative tax planning. We don't want them to be in tax havens."

FUND'S SUBSIDIARIES

Most of the fund's assets are held in stocks and bonds, but it also owns stakes in more than 800 properties in Europe and the United States, with much of the ownership organised through subsidiaries in Luxembourg and the state of Delaware.

Among the arguments for this is to limit the fund's own tax costs, which has now come under scrutiny.

"We believe we will get a majority for a thorough probe into the fund's subsidiaries in Luxembourg and in Delaware to see if there is a better way to structure them. There needs to be a debate about this," Tvedt Solberg of Labour said.

The fund already has several areas where it aims to hold companies accountable, including child labour, climate change and water management. It is also forbidden from investing in some industries, including tobacco makers and producers of nuclear arms.