The political team that led Ukraine through last winter's Orange Revolution was on the verge of splitting yesterday as President Viktor Yushchenko's chief of staff said he was resigning because of corruption within the president's inner circle.

Olexander Zinchenko, who headed Mr Yushchenko's election campaign, called on the president to sack his national security council secretary, Petro Poroshenko, and his first aide, Olexander Tretyakov, whom Mr Zinchenko accused of "cynically realising their plan to utilise authority to their own purposes".