LONDON (Reuters) – British business minister Kwasi Kwarteng said on Tuesday he had written to petrol retailers over concern a cut in fuel duty was not being passed on to consumers, adding he had asked the competition regulator to investigate. The Times newspaper had earlier reported that a 5 pence cut in duty, announced by the government in March, was not being passed onto motorists who have seen prices soar due to a surge in oil prices worldwide. Kwarteng wrote to the heads of the Petroleum Industry Association, the Fuel Distributors Association, the Petrol Retailers Association and the Downs…