Calyon, the investment banking arm of France's Crédit Agricole, has defended itself against allegations by human rights groups that its part in a $2bn (€1.7bn) loan to Angola will undermine international efforts to fight corruption in the country.

Calyon said the syndicated loan to Sonangol, the Angolan state-owned oil company, had been subjected to compliance controls and due diligence. The company said: "The finalisation and execution of the transaction is in accordance with the strictest compliance rules used in the banking market."