The government of Ghana on Tuesday night said it would renegotiate Vodafone’s $900m purchase of Ghana Telecom, a leading local group after an official review into alleged “irregularities” in the deal. The dispute is a potential blow to the world’s biggest mobile provider by revenues, which has been expanding in emerging markets – Africa among them – to seek faster growth. The UK’s Serious Fraud Office on Tuesday said it had contacted Vodafone regarding the deal, though it has not launched an investigation.