Kazakhstan yesterday threatened to revoke the licence of a consortium led by Italy's Eni to develop the vast offshore Kashagan oil field over environmental violations, stepping up the pressure as it seeks a review of the project's terms.

Just one day after Eni and the Kazakh government began talks on the future of the project, Nurlan Isakov, the country's environment minister, said the work of the Agip KCO consortium, which also includes Shell, Exxon Mobil and ConocoPhillips, could be stopped due to environmental concerns.