ADDIS ABABA, Ethiopia — Sudan vowed Wednesday to confiscate a portion of South Sudan's oil as it passes through a pipeline in Sudan as talks between the countries failed to produce any agreement on how to split oil revenues.

Sudanese officials defended the action as a reasonable step to bolster their country's flailing economy, which lost access to oil production facilities earlier this year when South Sudan became independent.

Several months of negotiations have failed to produce a deal on how much South Sudan should pay to move its oil north through a pipeline that runs through Sudan.

South Sudan denounced Sudan's plan, and mediators from other African nations expressed frustration that six days of talks hadn't ended in an agreement. Former South African President Thabo Mbeki oversaw the talks.

Sudan said it would take only a portion of South Sudan's oil and that the rest would be allowed to flow to ships for export.

South Sudan's chief negotiator, Pagan Amum, called the solution "extortion" and "looting" and said no agreement had been reached because Sudan was asking for too much.

According to South Sudanese officials, two shipments totaling 1.6 million barrels were delayed in Port Sudan but the ships have since been loaded and were expected to be released soon. One of those shipments belonged to a Chinese oil firm, prompting a rare public reproach by the Chinese Foreign Ministry in Beijing, urging both sides to keep the oil flowing.

Sudan pledged to continue negotiating, and said it wouldn't block shipments of South Sudanese oil.

"We are never going to shut down the pipeline. We will take from the oil in kind what we deem to be our dues," Said al Khatib, a senior member of the Sudanese delegation, said in an interview Wednesday. "We will stick to what we feel is our fair share."

Sudan won't grab more than 30 percent of the oil, Khatib said. Another member of the Sudanese delegation said it probably would be around 23 percent.

International reaction is still uncertain.

By the time the oil reaches Sudanese territory, the South Sudanese government already has sold it to a third-party buyer. Amum said he doubted that Sudan could stop foreign companies from claiming their paid-for commodity, and that he considered the latest news merely an intimidation tactic.

Sudan's Khatib said that would be a problem South Sudan would have to sort out with its business partners.

"This is something that they have been notified of. So when they sell, they know now that whatever they sell, some of that is ours. So they need to make that clear to the buyers," Khatib said.

(Boswell is a McClatchy special correspondent.)

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