Umaru Yar'Adua, Nigeria's president, has sacked two ministers on suspicion of stealing public funds, a sign he is adopting a more assertive style after surviving a legal challenge last month to his election victory.

The ministers were the first to be forced out since Mr Yar'Adua appointed his cabinet in July, three months after winning elections so badly flawed that many Nigerians believed they barely merited the name.