Moscow ratcheted up pressure on BP's Russian venture yesterday, warning that TNK-BP could see the licence for its vast Kovykta gas field revoked within "amatter of days".

Oleg Mitvol, head of Russia's environmental watchdog, said his agency would open a probe tomorrow into whether TNK-BP was meeting licence terms to develop the east Siberian field - as a three-month deadline passed for production there to be boosted to 9bn cubic metres in line with requirements.