The U.S. House of Representatives has overwhelmingly passed a bill to increase pressure on investors in Iran's energy sector.

The bill requires the naming of foreign companies with more than $20 million invested in Iran's energy sector.  It also offers protection to private investment managers and state and federal pension funds that divest from companies on the list.

The measure passed by a vote of 480 to six.  Democratic representative Brad Sherman says the bill is aimed at changing the behavior of those who still invest in Iran, which the U.S. accuses of supporting terrorism and seeking nuclear weapons.

The House passed a similar bill, 418 to one, earlier Tuesday to promote divestment from firms that do business in Sudan.  United Nations officials estimate the four-year conflict in Darfur has killed more than 200,000 people, and displaced 2 million more. 

Senator and presidential hopeful Barack Obama has introduced a similar measure on Iran in the Senate.

Some information for this report was provided by AFP and Reuters.