UNITED NATIONS -- President Obama is using his third and last day at the U.N. General Assembly to focus on averting renewed conflict in Sudan and easing growing maritime tensions between China and its Southeast Asian neighbors.

A day after concentrating on broader international issues, Obama on Friday was to attend a high-level U.N. meeting aimed at ensuring an upcoming independence referendum for southern Sudan does not spark a new civil war. Preparations for the January vote are well behind schedule, and there are fears a vote to secede will lead to violence.

In preparatory meetings this week, Secretary of State Hillary Rodham Clinton has been urging Sudanese authorities to make up for lost time in preparing for the referendum that is called for in the 2005 peace agreement that ended 21 years of north-south civil war in the African nation.

Southern Sudan, which is predominantly animist and Christian, is scheduled to vote on independence Jan. 9. But the group charged with organizing the vote has not yet set a date for voter registration.

The Obama administration has said it is "inevitable" the south will declare independence. Given the south's substantial known oil resources, many worry that the predominantly Muslim north will find it difficult to accept an independent south.

The president also will host a luncheon for leaders from the 10 members of the Association of Southeast Asian Nations who are concerned about increasing Chinese assertiveness in the South China Sea. To China's annoyance, the Obama administration has declared a peaceful resolution to territorial disputes in the sea to be in the United States' interest.

The meeting follows Obama's talks on Thursday with Chinese Premier Wen Jiabao and Japanese Prime Minister Naoto Kan, whose countries are embroiled in their own dispute over jointly claimed islands in the East China Sea.

Beijing was furious when Clinton told a regional security forum in Vietnam in July that the peaceful resolution of disputes over the Spratly and Paracel island groups in the South China Sea was in the U.S. national interest. Beijing said Washington was interfering in an Asian regional issue.

The United States worries the disputes could hurt access to one of the world's busiest commercial sea lanes.

China claims all of the South China Sea, where Vietnam, Taiwan, Malaysia, Brunei and the Philippines also have laid territorial claims. Aside from rich fishing areas, the region is believed to have huge oil and natural gas deposits. The contested islands straddle busy sea lanes that are a crucial conduit for oil and other resources fueling China's fast-expanding economy.

At Friday's lunch, Obama is also expected to press Myanmar's military rulers to hold free and fair elections this year and release political prisoners, including democracy activist Aung San Suu Kyi, who is under house arrest. U.S. officials have said they see little chance that any polling there will meet international standards.

In addition to the group meetings, Obama also plans separate talks with the leaders of Colombia, Azerbaijan and Kyrgyzstan.