The United States has said it may remove Sudan from its list of state sponsors of terrorism if the government in Khartoum recognises the outcome of the south's referendum on whether to split from the north.
"Should the referendum be carried out successfully and the results are recognised by the government, President Obama would indicate his intention to begin the process of removing them," Princeton Lyman, the lead US negotiator with Sudan, said on Tuesday.
"It is a process that takes some time, but by beginning the process in the wake of the referendum, the hope is if they meet all the conditions it can be done by July."
Lyman made the remarks on the third day of voting in the referendum, which was organised as part of a peace agreement in 2005 that ended two decades of civil war between the north and the south.
The referendum is widely expected to lead to mainly Christian and animist southern Sudan seceding from the predominantly Muslim north of the country.
Bashir praised
Omar al-Bashir, the Sudanese president, has been praised for saying that he will celebrate the outcome of the poll whatever it may be and will work with an independent south Sudan if it chooses to secede.
However, the vote has been mared by sporadic acts of violence between pro-Khartoum tribes and southern security forces and attacks on southerners heading from the north to vote.
Officials in south Sudan said 10 people were killed when their convoy was ambushed by Misseriya nomads in Southern Kordofan on Tuesday.
Johnnie Carson, the assistant secretary of state for African affairs, said another key condition for removing Khartoum from the US blacklist is that it does not "directly or indirectly" support "terrorist" groups.
Countries on the list of state sponsors of terrorism cannot receive US aid or buy US weapons, and bilateral trade is restricted. The list currently includes Cuba, Iran, Sudan and Syria.
The United States has banned virtually all trade with Sudan since 1997.
