The price of petrol was today decreased by 58 paise per litre and that of diesel by 25 paise. Diesel rates were not changed on November 1, however, it increased by 95 paise on October 16 and 50 paise on October 1. Rates of diesel were decreased by 50 paise on September 1.Previous to the November 16 increase, petrol price had been decreased on four occasions — by Rs 2.43 on August 1, Rs 1.27 on August 16, Rs 2 on September 1 and 50 paise on November 1. State-owned fuel retailers — IOC, Bharat Petroleum Corp (BPCL) and Hindustan Petroleum Corp (HPCL) — revise petrol and diesel prices on 1st and 16th of every month based on average imported cost and rupee-dollar exchange rate in the previous fortnight.The IOC statement said that the movement of prices in the international oil market and INR-USD exchange rate shall continue to be monitored and developing trends of the market will be reflected in future price changes. The prices will become effective from midnight tonight.