The BBC's Cathy Jenkins reports from the battle line

Reports from northern Ethiopia say at least 35 people - including 10 children - have been killed in an Eritrean air raid on the town of Mekele.

Earlier, Eritrean anti-aircraft guns shot down one Ethiopian plane during an attack on the airport in the capital, Asmara. There was another Ethiopian raid to the south-east of the city.

One man on an access road was killed and four people injured.

Ethiopia said the attacks were in retaliation for an earlier Eritrean air raid on Mekele, in which five people were wounded.

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A foreign journalist who witnessed the bombing near the airport said two fighter jets were involved.

A BBC correspondent in Asmara says roads to the airport became jammed as jubilant Eritreans flocked to see the wreckage of the enemy jet.

The Eritrean Government had earlier accused Ethiopia of wanting all-out war.

Evacuation

Foreign nationals, advised by their governments to leave Asmara, have been gathering at consulates and embassies, but it is not clear whether they will be able to leave.

The American and British governments have been planning to bring in special planes to evacuate their nationals.

Meanwhile, the Eritrean Foreign Minister, Haile Weltensae, speaking at the Organisation of African Unity meeting, said Ethiopia has given his government seven days to cut its diplomatic presence in Addis Ababa to three people, and to close two consulates.

Heavy fighting

Prior to the air raids the two sides had been fighting with heavy artillery, mortars and small arms across a broad valley in the mountainous Alitena region.

Both sides have blamed the other for the fighting

The Eritreans said the Ethiopians were forced back to what the Eritreans say is the international border.

Both sides have accused the other of launching the offensive, which caused thousands of refugees to flee.

The Eritrean Foreign Ministry described the Alitena clash as a dangerous escalation of a border dispute between the two countries, which until recently enjoyed friendly relations. It said this was the fourth attack by Ethiopia in less than two weeks.