The beleaguered chief executive of BP's Russian oil joint venture abruptly left the country yesterday, blaming mounting uncertainties over his visa and "sustained harassment".

As Robert Dudley left, Tony Hayward, BP's chief executive, told the Financial Times that the UK company was "not going to be intimidated by strong-arm tactics" into allowing the Russian tycoons who own the other 50 per cent of TNK-BP to take control.