Most leading oil multinationals fall well short of best practice on revealing financial data and combating corruption, a survey unveiled today by Transparency International…claims. The research says western companies such as ExxonMobil, ChevronTexaco and BP rank as middling or poor performers on voluntarily disclosing information about their operations - alongside China National Offshore Oil Corp, Russia's Lukoil and Petronas of Malaysia...In the report's rankings of 26 big oil companies…only Royal Dutch Shell of the largest multinationals wins entry to the eight-strong top bracket...Exxon and Chevron did not respond to requests for comment. BP said it never commented on external surveys.