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MEXICO CITY, July 5 (Reuters) - Mexican state oil and gas monopoly Pemex reported two explosions and a leak at gas and fuel pipelines in central Mexico on Thursday, but said there were no casualties and no major disruption to supply.

Pemex said a drop in pressure in the early hours of the morning alerted it to an explosion in a 36-inch natural gas pipeline running between the cities of Valtierrilla and Guadalajara.

A second explosion shortly afterward further along the same pipeline also affected a 14-inch pipeline carrying liquid petroleum gas and a 10-inch gasoline pipeline.

Pemex also reported a leak from a 24-inch gasoline pipeline at the nearby town of Puerto, Guanajuato state.

All the ruptured pipelines were supplying the domestic market. There was no effect on Pemex's crude oil operations.

The cause of the explosions was not known.

No casualties were reported in the affected municipalities of Celaya and Salamanca in Guanajuato state, but authorities evacuated several thousand residents from nearby communities.

The explosions set off two raging fires, but Pemex said one was extinguished and the other had been brought under control by midday.

State-controlled Pemex regularly suffers accidents and spills along its network of aging oil, gas and fuel pipelines, drawing fire from environmentalists.

Separately on Thursday, Pemex said heavy rains caused a gasoline pipeline to rupture in the grimy Iztapalapa district of Mexico City.

Mexico is a top supplier of crude oil to the United States, but is a net importer of natural gas and gasoline.

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