Norway has stopped investing in seven companies which it says are involved in the production of nuclear weapons.
Norway says nuclear weapons violate human rights
Oslo said it was no longer investing money, via its state pension fund, in companies whose activities "violate fundamental humanitarian principles".
The companies concerned include UK defence firm BAE Systems and US firms Boeing, Honeywell and Northrop Grumman.
Norway invests a large slice of its huge oil wealth in foreign shares, with about $190bn invested overseas.
The Norwegian government said shares worth about $500m (£286m) had been sold in the companies at the end of 2005.
Finance minister Kristin Halvorsen said the centre-right government of Kjell Magne Bondevik had taken the decision before it was voted out of office in September.
Ms Halvorsen said the current Labour administration supported its predecessor's action, based on recommendations it had received from the fund's Ethics Council.
The seven companies excluded from the fund are BAE Systems, Boeing, Northrop Grumman, Honeywell International, Finmeccanica, Safran and United Technologies Corporation.
Oslo said it had based its decision on information available on the companies' websites as well as independent analysis.
It said it had asked each of the companies concerned to clarify their position regarding nuclear weapons.
One confirmed its involvement, the Ministry said, while the other six either did not reply or declined to discuss the subject.
"According to the ethical guidelines for the Government Pension Fund - Global, companies that produce weapons that through normal use may violate fundamental humanitarian principles shall be excluded," the Finance Ministry said in a statement.
"Nuclear weapons are considered to be in this category of weapons."
Further companies could be excluded from the fund in the future, it added, if found to be involved in the manufacture of nuclear weapons.
The fund - formerly known as the state petroleum fund - is one of the world's largest pension funds.
It is managed by Norway's Central Bank under government guidelines.
Norway is opposed to the proliferation of nuclear weapons although it remains a member of NATO, several of whose members have a military nuclear capacity.