WASHINGTON — The Federal Trade Commission is broadening its monitoring of gasoline markets around the country to gather information on daily price changes in an attempt to focus quickly on any unusual price spikes, the agency said.

FTC Chairman Timothy Muris said the agency has begun using a statistical model that is expected to track price spikes as they happen to identify factors contributing to the price fluctuations.

Data on retail gasoline prices, using credit card purchases from thousands of service stations in 360 cities, will be plugged into the model as will daily information on wholesale prices from 20 major urban areas, the agency said.

Retail prices have increased substantially since the first of the year, although they have leveled off in recent weeks. The average price of regular gasoline this week was $1.40 a gallon, 31 cents cheaper than at the same time a year ago, according to the Energy Information Administration.