A 7.4-magnitude earthquake has killed dozens of people in the central American country of Guatemala, although no tsunami alert has been issued.

The Pacific coast of the country is bearing the brunt of the quake, which has so far killed at least 48 people and injured more than 155.

Experts said the epicentre of the quake was in the Pacific Ocean, 200 kms southwest of Guatemala City, and had a depth of 5.4 kms. Authorities say this has been the strongest earthquake since 1976.

Scores of people fled their homes for open areas as the quake struck, and dozens of buildings have been wrecked across several towns.

Electricity supply and road transportation have been crippled by snapping power lines and landslides.

Three helicopters are engaged in emergency measures, airdropping food and essentials into the affected areas. The government has asserted it has enough emergency supplies to tackle the situation.

"It's very sad to meet people here who are waiting to find their families who are still buried. It's really a tragedy and we will do all we can to help the families that are suffering," said President Perez Molina.

A three-day period of national mourning has been declared by the government.