A nationwide Sudan divestment campaign heads to...Omaha, Neb., home of billionaire Warren Buffett and his Berkshire Hathaway Inc. company... [A]ctivists Saturday will try to persuade the renowned investor and Berkshire's shareholders to unload 2.3 million shares in [PetroChina] because of its business ties in war-torn Sudan... [A]ctivists say PetroChina's parent company, government-owned China National Petroleum Corp., is the largest investor in Sudan's growing oil industry... At the same time, activists are mounting a similar media blitz to prod mutual fund giant Fidelity Investments to dump millions it has invested in PetroChina... Fidelity spokeswoman Anne Crowley said she could not comment on the company's PetroChina investments but said the activists' information on Fidelity's holdings is 4 months old. She said Fidelity isn't violating any U.S. laws and the government should decide what foreign investments are appropriate... Major European companies, such as...Siemens...and...Rolls-Royce..., have announced plans to pull out of Sudan... CalPERS, which owns nearly 7,500 shares...in Berkshire, will oppose [the resolution]... Buffett has defended the investment, saying China National operates in Sudan and that PetroChina shouldn't be held accountable for actions of its corporate parent. Berkshire officials also argue that a pullout by China National could put more oil assets in the hands of the Sudanese government.