* World's biggest wealth fund to vote against Exxon, Chevron
* Says oil firms should do more to report climate risks (Recasts with comments from fund's CEO)
By Alister Doyle and Gwladys Fouche
OSLO, May 3 (Reuters) - Norway's $872-billion sovereignwealth fund, the world's largest, said it would press U.S. oilmajors ExxonMobil and Chevron to do more toreport on the risks of climate change.
The fund said on Tuesday it would vote in favour ofshareholder proposals, opposed by both companies' boards, whichwould require them to report more fully about the risks andopportunities of a changing climate.
Royal Dutch Shell and BP adopted similarpolicies last year, following shareholder pressure, it said.Exxon and Chevron both say they are already doing enough toreport on climate risks.
"We want them to be open about their climate strategy andtheir dialogue with regulators," the fund's chief executiveYngve Slyngstad told reporters.
Firms should be clear about risks, both from the impacts ofclimate change such as floods and storms, as well as fromgovernment policies to curb carbon emissions, he said.
The fund, itself built from Norway's oil and gas wealth, wasmaking similar demands of oil firms worldwide and would keepgoing even if the resolutions were defeated at Exxon's andChevron's annual general meetings, both on May 25.
"We will then come back next year and the year after," hesaid. Norges Bank Investment Management (NBIM), which managesthe fund, was the seventh-largest shareholder of both firms atthe end of 2015, Thomson Reuters Eikon data shows.
Slyngstad said the fund, which owns about 1 percent oflisted equities worldwide, had 4,000 meetings with majorcompanies a year to discuss its investments.
He said many companies were planning to cut their greenhousegas emissions by 40 percent in coming years to help achievegoals set at a 195-nation Paris summit on climate change inDecember that include phasing out emissions by 2100.
Companies "have to explain if they don't intend to reducetheir emissions to that extent," he said.
The fund said last week that it may exclude another 40companies for using coal in their operations after divestingfrom 52 since Norway's parliament last year told it to sell outof firms that get more than 30 percent of their turnover oractivity from coal.
Slyngstad said it was hard to set firm rules, saying a powercompany generating 30 percent of its electricity from coal and70 percent from wind might stay in the portfolio ahead of a firmusing 30 percent coal and the rest fossil fuels.
"The fund is like a supertanker, It takes some time to turnit."
At the end of 2015, NBIM said it held a 0.78 percent stakein Exxon, valued at $2.54 billion, while its 0.85 percentholding in Chevron was worth $1.45 billion. (Additional reporting by Terje Solsvik; Editing by Jason Neelyand Alexander Smith)