China will cut retail gasoline and diesel-fuel prices for the third straight month, according to state-run television, which could help Chinese consumers and give the government more room to juice a slowing economy.

China Central Television cited Zhou Wangjun, the deputy director of the pricing department at the National Development and Reform Commission, in a report on its website on Monday.

"We will cut refined-oil-product prices on Wednesday when it meets the price-adjustment window," said Mr. Zhou, without specifying the size of the cuts.

The NDRC, China's top economic-planning body, sets fuel prices based on a basket of international crude types, though it hasn't always rigidly followed the formula. It had already cut prices twice since May, as global crude prices have eased. As of Friday, energy consultancy ICIS C1 Energy said, the value of the crude basket was down about 9.5% from the June 7 price—the level on which the last price cut was based.

The coming cut is expected to be between 400 and 600 yuan (about $63 to $94) a metric ton, analysts said, or as much as 6.6% and 7.2% for gasoline and diesel, respectively. The current average retail ceiling benchmarks are 9,120 yuan per metric ton for gasoline and 8,310 yuan per ton for diesel. Because the two fuels have different densities, gasoline is cheaper by volume despite being costlier by weight—the benchmarks translate to $4.01 per gallon for gasoline and $4.17 per gallon for diesel, or $1.06 and $1.10 per liter.

Lower fuel prices would add to China's disinflation trend, which has made the government more comfortable in cutting benchmark interest rates and reforming energy prices. China's consumer inflation eased sharply in June, with prices up 2.2% from a year earlier, compared with May's 3% pace, the National Bureau of Statistics showed Monday. Growth in the consumer price index has slowed for four consecutive months.

Declining prices also make consumers more likely to accept reforms. The NDRC already has started a nationwide trial of progressive pricing for residential electricity users amid lower benchmark coal prices. But changes to China's system for retail oil prices will be implemented only when international oil prices are stable and heading down, the state-controlled Xinhua news agency reported in March, quoting an official then with the NDRC.

China's crude basket lags behind benchmark global oil prices, which jumped June 30 after the European Union reached a bank-bailout deal. Brent crude futures, for instance, which at one point were down as much as 11% since China's last fuel price adjustment, as of Friday were down just 1.7%.