A powerful earthquake measuring up to 7.3 hit off El Salvador's Pacific coast, triggering a brief tsunami alert for Central America and Mexico but causing no injuries or damage.

The warning was later canceled, and no huge wave was known to have made land in quake-prone Central America.

The tremor just before midnight Sunday local time unleashed at least 68 aftershocks, a few of them measuring as much as 5.4, the Environment Ministry said.

The epicenter of the tremor, which occurred at 0437 GMT, was located 111 kilometers (69 miles) south of the city of Puerto El Triunfo in El Salvador, according to the US Geological Survey.

Following the quake the Pacific Tsunami Warning Center issued an alert, saying that the temblor, which took place at a depth of 54 kilometers (36 miles), had spawned a tsunami.

A short time later, however, the center cancelled the warning.

Salvadoran Civil Protection Service Director Jorge Melendez said there had never been a tsunami threat.

Melendez said the quake hit so far off the coast it was barely felt in El Salvador.

He said his agency did not issue an official tsunami alert, but people living along the coast should maintain "a certain level of vigilance."

The earthquake reading was based on the open-ended Moment Magnitude scale used by US seismologists, which measures the area of the fault that ruptured and the total energy released.

The initial USGS report put the strength of the quake at 7.4, but it was later revised to 7.3.

The quake was not the first reported in the region in the last 24 hours. Early Sunday, a 4.3 tremor was registered in the Pacific off the coast of Guatemala.