Ethiopia attacked an Eritrean military base on Thursday in response to the killing earlier this year of five European tourists in Ethiopia's Afar region, a government spokesman said.

"Early this morning Ethiopian defence forces attacked a military post inside Eritrea ..." spokesman Shimeles Kemal told reporters, accusing Eritrea of using the base to train and arm "hit-and-run terrorists".

"These groups are operating in Afar area in Ethiopia," said Shimelese.

"We know for certain that the Eritrean government harbours, supports, trains and deploys subversive groups that occasionally launch attack on infrastructure inside Ethiopia."

Shimeles said the attack took place 16 kilometres (10 miles) inside Eritrea but was unable to confirm the number of casualties from the Ethiopian or the Eritrean side.

In January, two Germans, two Austrians and one Hungarian were killed in an attack on the slopes of Ethiopia's famed Erta Ale volcano in the remote Afar region.

Ethiopia blamed arch foe Eritrea for the attack on the tourists, charges that Eritrea denied.

"The recent attacks against European tourists is one of the reasons for this retaliation," Shimeles said.

The attack on the tourists had rekindled tensions between the two Horn of African nations, raising fears of another war between the two countries.

Shimeles said war was not likely to erupt between the two countries, insisting that Ethiopia was committed to peaceful negotiations. But he warned that Ethiopia could launch further attacks in response to security threats from Eritrea.

"As long as Eritrea remains a launching pad for attacks against Ethiopia, similar measures will continue to be taken," he said.

If Eritrean forces retaliated, he warned, "the results would be disastrous."

Eritrea broke away from Ethiopia and won independence in 1993 after a 30-year struggle. The two countries fought a devastating 1998-2000 border war, which claimed at least 70,000 lives.