"Spontaneous returnees, most of whom are returning empty handed, will place additional demands on the fragile local food supplies due to erratic rains in 2004 and the few amenities in healthcare, schools and clean drinking water points," ACT said on Friday in a statement.
The IDPs and refugees have been returning, at an average of 1,500 daily, since the signing of a peace agreement that ended two decades of civil war in southern Sudan. Former rebels of the Sudan People's Liberation Movement/Army and the Sudanese government signed the agreement on 9 January in the Kenyan capital, Nairobi.
ACT said the money would be used on health care, education, agriculture, water, transport and poverty alleviation programmes.
There are about four million IDPs in Sudan, 3.5 million of whom are southerners living in the north of the country. They are mainly housed in IDP camps on the peripheries of the cities of Khartoum and Omdurman, according to ACT.
It is estimated that there are another 500,000 southern Sudanese refugees in the neighbouring countries of the Central African Republic, Egypt, Eritrea, Ethiopia, the Democratic Republic of Congo, Kenya and Uganda.