Mexico closed seven service stations Thursday for allegedly selling gasoline and diesel stolen from state-run pipelines, the first confirmation that large amounts of fuel siphoned from illegal pipeline taps are being sold through officially sanctioned gas stations.

An official of the state-run Pemex oil company said authorities had caught red-handed such sales at a total of 14 stations — seven in Puebla, one of the states hit hardest by pipelines thefts, and seven elsewhere in Mexico. The official didn't say why only seven had been shut down.

MEXICO TARGETS SUPPLIERS, BUYERS IN MOVE AGAINST FUEL THEFT

The thefts were especially brazen, given that the stations were selling fuel stolen from their own supplier. Pemex runs Mexico's pipelines and supplies the approximately 12,000 official gas stations under a concessionary agreement. Thus, the company knows about how much a station and pump dispatches and whether that matches up with what was supplied.

At the 14 stations, the numbers didn't add up.

"They stopped buying (gasoline) and they continued selling it," said the Pemex official, who was not authorized to be quoted by name.

Observers have long said the amount of fuel taken in widespread pipeline thefts is too much to be sold from plastic containers by the side of the road. Many experts have long believed some of the gasoline and diesel siphoned off by illegal pipeline taps is being sold to businesses or at gas stations.

MEXICO SLOWS DECLINE IN OIL RESERVES

The phenomenon has become so widespread that officials say entire towns have been involved in protecting fuel thieves or benefiting from the trade.

In May, gunmen used residents of a small Puebla town as human shields and opened fire on army patrols investigating pipeline thefts. Four soldiers and six suspected criminals were killed in the clashes.

Treasury Secretary Jose Antonio Meade said this week that more than 6,000 illegal pipeline taps had been found in 2016 and officials have been detecting an average of about 20 taps a day this year. Earlier, he estimated that fuel theft costs the country about $1 billion a year.

EXXON MOBIL TO ENTER MEXICAN GAS-STATION MARKET

The closure announcement Thursday was the first significant crackdown on such stations, though at least one station had been detected in the northern city of Monterrey as early as 2012.

There have been suggestions before that fuel theft was occurring on an industrial scale in Mexico.

In June 2012, the Mexican navy seized a Mexican-flagged ship in the Gulf of Mexico heading toward Honduras with nearly 80,000 gallons (300,000 liters) of stolen diesel aboard, presumably from Pemex. The next month, the navy caught another ship in the Gulf with nearly 106,000 gallons (400,000 liters) of presumably stolen diesel.