WASHINGTON -- An earthquake measuring 6.8 struck in the Atlantic Ocean early Friday, hundreds of kilometers (miles) off the northern coast of Brazil and French Guiana, the US Geological Survey reported.

The Pacific Tsunami Warning Center said there was a small possibility a local tsunami could hit coasts in countries within and bordering the Caribbean Sea, but ruled out "a destructive, widespread tsunami threat."

The quake struck at 0938 GMT, at a depth of 10 kilometers (six miles) along the northern mid-Atlantic ridge.

Its epicenter was located 1,316 kilometers (818 miles) east-northeast of Cayenne, the capital of French Guiana, and 1,530 kilometers (950 miles) north-northeast of the coastal city of Belem, in Para state, Brazil, it said.

"A destructive widespread tsunami threat does not exist based on historical earthquake and tsunami data," the Pacific Tsunami Warning Center said in a bulletin issued shortly after the quake.

"However, there is a small possibility of a local tsunami that could affect coasts located usually no more than a hundred kilometers from the earthquake epicenter," it said.

It said the statement pertained to countries within and bordering the Caribbean sea, except for Puerto Rico and the Virgin Islands.