Jonah Fisher BBC, Asmara

The UN has launched a security assessment of its operations in the far west of Eritrea after two bombs exploded destroying aid trucks.

There have been no casualties reported but this is the biggest in a series of explosions in Tesseney on the border with Sudan.

No organisation has yet claimed responsibility for the attacks - though previous attacks in the area have been blamed on a Jihad terrorist group.

The bombs went off on Friday evening underneath two trucks carrying World Food Programme aid. Five minutes after the drivers left their vehicles, devices detonated under each vehicle.

Both were extensively damaged and a large amount of the food destroyed.

Repeated attacks

Tesseney is a town on the border with Sudan and has been the site of a number of explosions in recent weeks.

A truck near a petrol station and a cafe teashop were both targeted - though there have been no casualties in any of the attacks.

The Eritrean government has played down the significance of the spate of bombings - blaming it on localised arguments and quarrels and said they were not unduly concerned by them.

This is part of the country where the Eritrean Islamic Jihad group are thought to operate. It is only three hours walk from Kassala in Sudan - and though the border is closed it is still extremely porous.

In April, a British geologist was brutally killed while prospecting for gold in the nearby countryside. The Eritrean government blamed it on the Islamic Jihad group with backing from the Sudanese government.

Tesseney is the Eritrean base for refugee repatriations from the Sudan so it has a significant UN presence. They are now despatching a security team to assess what measures they should take in response to the bombs.