The Ethiopian aid organisation said it was collaborating with the International Federation of Red Cross and Red Crescent to provide the new arrivals who fled the South Sudan crisis with medical care and basic services.
Ariane Tombet, Head of the ICRC delegation in Ethiopia, said the 12,000 were among those who arrived recently.
More than 95,000 South Sudanese had fled to the neighbouring Ethiopia camp since the violence broke in December 2013.
The number is expected to rise following the recent violence in some parts of the country that left more than 200 dead and many others injured, with more fleeing to neighbouring countries, including Kenya, Sudan and Uganda.
The Secretary-General of the Ethiopian Red Cross, Frehiwot Worku, told NAN on Thursday in Addis Ababa that more refugees were arriving every day while the Red Cross ambulance crews were giving 24-hour service to refugees who needed medical attention.
“The rainy season will soon be upon us and with that comes the potential for an increase in water-borne diseases such as cholera and diarrhoea,
Meanwhile, the parties to the conflict had begun negotiations in Addis Ababa under the IGAD mediation in a renewed effort to resolve the political impasse between the President Salva Kiir and his former Vice President, Reik Machar. (NAN)