Senior U.S. officials say the United States is offering to drop Sudan from its list of state sponsors of terrorism if Khartoum successfully carries out next month's independence referendum in south Sudan.

The officials say the offer comes from President Barack Obama and was made through Democratic Senator John Kerry during a recent visit to Sudan.

Under the plan, Sudan would be dropped from the list in July 2011 if the referendum takes place on time and the Sudanese government respects the results, including on such matters as oil-revenue sharing and questions of citizenship.

Separate sanctions on Sudan over the conflict in Darfur would remain in effect.

South Sudan votes January 9 on whether it will become independent. Separately, voters in the oil-rich Abyei region would vote on whether to remain with the north or join the south.

But preparations for the two votes are far behind schedule. Both sides are also squabbling over who is allowed to take part in the Abyei vote.

The referendums are part of a 2005 peace deal that ended a long civil war between the north and south.

Along with Sudan, other countries currently on the U.S. state sponsors of terrorism list are Cuba, Iran, and Syria. Countries on the list face trade and other financial sanctions and are not eligible for U.S. aid or weapon sales.

Some information for this report was provided by AFP and Reuters.