(FORTUNE Magazine) -- Imagine this for a government conundrum: revenues so high it's hard to know how to spend them. No wonder Norway, flush from oil exports, is picky about where it invests its $236 billion government pension fund - the third largest on the planet.

In June it divested about $430 million worth of shares from Wal-Mart Stores (Charts) and Freeport-McMoRan Copper & Gold (Charts) after savaging Wal-Mart for "serious and systematic" labor violations in several countries and Freeport for dumping copper tailings in a New Guinea river.

Now officials say their cleanup campaign is just getting started. "We are working on how to act as shareholders in different companies," says Kristin Halvorsen, the leader of Norway's Socialist Left Party, who was appointed Finance Minister last October. "That is quite new for us."

The fund's portfolio includes holdings in 3,500 foreign companies, and Halvorsen says the list is being scrutinized for possible human-rights and environmental abusers. "The idea is to avoid complicity in the worst cases," says Henrik Syse, a philosopher recruited from a peace organization to head the team within Norway's central bank that administers the fund.

Halvorsen admits the list of potential culprits could be long, but she says that no country is disfavored and that her June decision had "nothing to do with Wal-Mart being American."

Earlier this year the fund sold off its holdings in companies involved with nuclear weapons and land mines, including Boeing (Charts), Honeywell International (Charts), and Northrop Grumman (Charts). About 40% of the remaining holdings - some $96 billion - is currently in U.S. shares and bonds, and investors who might otherwise ignore Norway are taking notice. Both Wal-Mart and Freeport stocks fell on news of Norway's divestment.

"Their public characterizations of us don't appear to be based on complete information," says Wal-Mart spokeswoman Beth Keck, adding, "We don't comment on investors' decisions."

No such promises from Norway, from which there's likely to be plenty more comment. Stay tuned.