Feb. 12 (Bloomberg) -- A 6.4-magnitude earthquake struck the southern Pacific coast of Mexico today, prompting the national oil company to shut down its largest refinery. There were no reports of injuries or major damage.

The earthquake hit at 6:50 a.m. local time, 40 miles (60 kilometers) northwest of the town of Tonala, Chiapas, the U.S. Geological Survey said on its Web site. Tonala is located between the states of Chiapas and Oaxaca. The temblor was 72 miles deep.

State oil monopoly Petroleos Mexicanos said it shut down its Salina Cruz refinery to assess potential damage. The refinery's 26 plants can process 290,000 barrels of crude daily and supply the entire Pacific coast, according to the Petroleos Mexicanos Web site.

The earthquake ``was pretty strong,'' Luis Manuel Garcia Moreno, the state's deputy secretary of civil protection, said in a telephone interview from Tuxtla Gutierrez, Chiapas. ``So far, we have had no reports of material damages or wounded.''

The quake was the strongest of the 40 in Chiapas this year, said Garcia Moreno. It followed a 5.1-magnitude quake that shook a remote area in Baja California yesterday and a 5.4-magnitude temblor in the same state last week that left 400,000 people without power and shut down factories, according to the Associated Press.

Pacific Coast

Today's quake was centered about 390 miles southeast of Mexico City, along the Pacific coast below Acapulco. The shock was felt in the capital as well as in the states of Tabasco, Veracruz, Puebla and the State of Mexico, Mexico City-based Grupo Televisa SA reported.

Elias Miguel Moreno Brizuela, Mexico City's Civil Protection Secretary, said no injuries or damages were reported there, according to an e-mail from his office.

Mexico's National Seismological Service located the temblor 44 kilometers southeast of Union Hidalgo, Oaxaca, and said it was a 6.6-magnitude quake. The USGS first reported the quake at magnitude 6.6, then later downgraded it to 6.4.

Southern Mexico accounts for 15 percent of the oil that Petroleos Mexicanos, or Pemex, produced in December. Pemex didn't say when it expects the refinery to reopen.

Carlos Ramirez, a spokesman for Mexico City-based Pemex, couldn't immediately be reached for comment.

To contact the reporter on this story: Valerie Rota in Mexico City at vrota1@bloomberg.net

Last Updated: February 12, 2008 13:36 EST