"The time-honored principles that Yale observes as an ethical institutional investor have guided us to take this strong action," Yale President Richard Levin said Wednesday in announcing the move.

He said he did not know the value of the stock, calling it "a small piece of a large fund."

The United States and international humanitarian groups have accused the Sudanese government of using its oil wealth to wage genocide against the people in the western Darfur region.

Levin said the university had stock in one of seven oil companies that it determined were providing "the lion's share of the revenue to the Sudanese government." Yale doesn't name its individual stock holdings.

Levin said the university would not invest in any of the seven, which he identified as: Bentini SPA, an Italian construction company that builds pumping stations; Higleig Petroleum Services and Investment Co. Ltd., a Sudanese company; Hi-Tech Petroleum, a Sudanese company; Nam Fatt Corp., a Malaysian construction firm that builds pumping stations; Oil and Natural Gas Corp., of India; PetroChina Co. Ltd.; and the China Petroleum & Chemical Corporation, or Sinopec.

The Yale Advisory Committee on Investor Responsibility, with help from Yale Law School's international human rights clinic, recommended the move, and Yale Corporation voted at a meeting last week to divest.