The decline in domestic fuel prices comes amid recent fall in global crude oil prices.New Delhi: Petrol prices on Monday declined to their lowest levels of 2018 across four metro cities, with fuel being sold at Rs 68.84 per litre in national capital.On Sunday it was priced at Rs 69.04 in Delhi, according to Indian Oil Corp's website.In Kolkata, Mumbai and Chennai, petrol prices fell to fresh lows of year, at Rs 70.96, Rs 74.47 and Rs 71.41 respectively, down from Rs 71.15, Rs 74.67 and Rs 71.62 per litre.The decline in domestic fuel prices comes amid recent fall in global crude oil prices.As per country's dynamic pricing mechanism, domestic fuel prices depend upon international fuel prices on a 15-day average and value of rupee.Oil prices, however, are likely to gain in days ahead as production cut by OPEC and non-OPEC countries comes into effect on January 1.In tandem with petrol prices, cost of diesel also registered a decline on Monday.Its price in Delhi, Kolkata, Mumbai and Chennai was Rs 62.86, Rs 64.61, Rs 65.76 and Rs 66.35 respectively against previous levels of Rs 63.09, Rs 64.84, Rs 65.76 and Rs 66.59 per litre.