The father of the Irish aid worker abducted in Ethiopia has said he understands direct contact was made with his son by Red Cross officials overnight.

Donal Ó Súilleabháin, 41, from Co Sligo, was travelling with six other colleagues when they were abducted by an armed group in the southern town of Godé at about 10am on Monday.

Five of the seven aid workers were subsequently released, but Mr Ó Súilleabháin and an Ethiopian colleague are still being held.

Mr Ó Súilleabháin, a hydro-geologist, has worked overseas for the Red Cross for several years and had recently travelled to Ethiopia from Darfur in Sudan.

Brian Ó Súilleabháin, Donal's father, told RTÉ News that it was his understanding from Red Cross officials that his son is in good form and is being well looked after by his captors.

A direct line of communication between the captors and the Red Cross has been established, and negotiations are continuing.

Brian Ó Súilleabháin said another of his sons, Eoghan, who is an aid worker with GOAL, has arrived in the Ethiopian capital Addis Abbaba.

Meanwhile, the Department of Foreign Affairs has said that one of its experienced negotiators is still en route to the region.

A spokesperson added that Minister for Foreign Affairs Dermot Ahern is being kept up to date on all developments.