Sudanese authorities could not immediately be reached for comment. The two countries' dispute involves an area where geologists say an intensive search for oil is under way.
Uganda's State Minister for Regional Cooperation, Okello Oryem, told Reuters South Sudanese officials demanded a 5 km (3 miles) portion of Ugandan land at a meeting on Dec. 12.
"It's true the Sudanese claimed ownership of a bigger chunk of land but of course we have colonial maps and other documents that clearly state where the border lies and I'm confident we'll reach an agreement when we meet in January," he said.
Sudan and Uganda have held meetings to try to iron out border disputes and Sudan demanded a 1 km strip of land earlier this year.
The latest Sudanese claim was made at a meeting in the West Nile town of Moyo that had been convened to resolve tensions sparked by attacks on Ugandan farmers by south Sudan's soldiers, Oryem said.
Instead, the leader of the Sudanese delegation, Muki Batali Bulli, made fresh claims on land he said had traditionally belonged to Sudanese tribes.
"They are basing their claims on old tribal settlements and we're saying that they are wrong," Oryem said.
The east African nation has been involved in a number of territorial disputes with neighbours and more similar incidents could arise owing to unclear demarcation lines drawn by the region's former colonial masters.
Earlier this year, Ugandan and Kenyan diplomatic relations were strained when they both claimed ownership of a rocky outcrop called Migingo Island on Lake Victoria.
The island's ownership is still undetermined because a joint demarcation committee set up to determine its location reached conflicting conclusions.
Uganda's military has also clashed with the Democratic Republic Congo army over Lake Albert, with Congo claiming that Uganda was encroaching on its territory. Commercial deposits of oil have been struck around the lake.
Uganda's President Yoweri Museveni and South Sudan leader Salva Kiir toured the border area in November in a bid to calm the bubbling conflict.
A geologist and retired commissioner of Uganda's Petroleum Exploration and Production Department, Reuben Kashambuzi, told Reuters that the chunk Sudan is claiming is in the Albertine Graben where there is much oil prospecting activity.
Uganda has already discovered an estimated 2 billion barrels of oil in the Graben.
- Reuters - Thomson Reuters Foundation
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