Most leading oil multinationals fall well short of best practice on revealing financial data and combating corruption, a survey unveiled today by Transparency International, the anti-graft group, claims.

The research says western companies such as ExxonMobil, ChevronTexaco and BPrank 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.