Efforts to repatriate Sudanese refugees from neighbouring countries have been stepped up before a census planned for Southern Sudan in early 2008, the UN High Commissioner for Refugees (UNHCR) said.

"We are gearing up our capacity to bring more and more people into Southern Sudan ... if you look at the figures in the first four months of this year we have brought more people than all of last year; this shows acceleration is taking place," António Guterres, the commissioner, said in the Southern Sudanese capital of Juba on 19 June.

Guterres arrived in Juba to celebrate UN World Refugee Day on 20 June. Earlier, he had travelled in a UNHCR repatriation convoy with 161 refugees from Moyo in northern Uganda to Kangai way station in Southern Sudan.

"Life will not be easy; you will face many difficulties," he told the returnees, the latest of nearly 155,000 South Sudanese to have made the journey from nearby countries since December 2005. "You are going back home and you need to have education for your children, healthcare for your families, agricultural land for farming and other support. All of this is only possible if there is strong solidarity from the international community."

UNHCR has about 686,000 Sudanese refugees living in various countries under its mandate. It also caters for 460,000 Somali refugees, while the numbers from the Democratic Republic of Congo (DRC) and Burundi were estimated at 400,000.

Operations for UNHCR-assisted returns of Sudanese refugees from the Central African Republic were completed in April 2007 and those from the DRC in June. A total of 15,536 Sudanese were helped to go back home.

"Whenever it is possible we're shutting down camps ... there are always residual groups, and we are trying to solve this problem with local government and finding solutions for these people," Guterres said in Juba.

UNHCR, he added, was now turning its attention to camps in Uganda and Kenya where massive registration had been going on in readiness for refugee repatriation to Southern Sudan.

Hundreds of thousands of people fled Southern Sudan after the outbreak of civil war in 1983. The war formally ended in 2005 with the signing of the Comprehensive Peace Agreement between the government and the former rebel Sudan People's Liberation Movement, which transformed itself into the semi-autonomous Government of Southern Sudan after the pact.

To ensure as many people as possible were repatriated, Guterres said UNHCR would continue to provide transport for those willing to go back to Sudan throughout the rainy season.

Observers have, however, expressed misgivings about the timing, saying returnees would likely face difficulties as they would be arriving too late to prepare land for planting and struggle to set up shelter.

UNHCR was criticised by Southern Sudanese authorities earlier in 2007 for allegedly being too slow to bring back refugees. Guterres said his agency was purchasing more lorries and improving repatriation efforts, despite limited funding.

"We fully share the anxiety of the government [which] has a very legitimate will that when the census takes place a large number of people are in Southern Sudan. We have diverted funds from other operations [to finance repatriation]," he said.

As well as refugees, UNHCR has been helping internally displaced people (IDPs). At the end of 2006, the total number of conflict-related IDPs worldwide was estimated by the Norwegian Refugee Council's Internal Displacement Monitoring Centre at 24.5 million.

The UN has assigned UNHCR an additional responsibility for protection, emergency shelter and camp coordination and management in IDP situations in a number of countries, including Uganda, DRC, Liberia and Somalia.