Mexican state oil monopoly Petroleos Mexicanos has launched a pilot program that will use tank trucks to supply compressed natural gas to factories and businesses in cities not connected to the country's gas pipeline network.

The program will begin in the northwestern state of Sonora, whose government has signed a contract with Pemex, and will help "reduce costs and improve the environment," the company said Wednesday in a statement.

Pemex will divert some of the gas transported by pipeline in that border state to a compression plant, where it will be loaded into cylinders for transport via tank truck to customers.

"Under this program, gas can be shipped to medium-sized cities where the industrial sector is currently using higher-cost fuels that generate more environmentally harmful emissions," such as diesel and fuel oil, Pemex said.

Because natural gas is cheaper than those other fuels, factories and businesses also will benefit from reduced operating costs.

Natural gas use in Mexico accounts for more than 50 percent of the energy market "because it's a clean fuel compared with other fossil fuels such as heavy fuel oil, diesel or (liquefied petroleum gas)," the statement said.

The pilot program will enable shipments of natural gas to the medium-sized Sonora cities of Navojoa, Guaymas, Ciudad Obregon, Huatabampo and San Luis Rio Colorado.

In Sonora, the tank trucks will have to cover distances of between 40-360 kilometers (25-223 miles) to distribute the natural gas to customers.

Deliveries will begin at the end of this year in San Luis Rio Colorado and in March 2012 in other cities south of Hermosillo, the state capital.

Pemex will partner with ET Internacional, which was awarded a contract to supply natural gas compression, transportation and decompression services, and together they will form a joint venture known as Tecno Energy that will market the gas in Sonora.

Pemex said it plans to repeat this overland natural gas transportation model in other areas of the country.