Guardian: BP has been accused by a senior US politician of lying to Congress to reduce its liabilities, after an internal company document showed that the oil giant’s own worst-case assessment of the size of the oil leak in the Gulf of Mexico was 20 times its public estimate. In the document, BP attempts to put a figure on the rate of oil spewing into the ocean. It notes that if the condition of the well bore deteriorates to the extent that crucial parts fall off, the rate could reach 100,000 …