* Jan Dar Blend exports to be about 21 pct less than planned
* Nile Blend exports cut after production halt in South Sudan (Adds Dar Blend's capacity in paragraph 7)
By Florence Tan
SINGAPORE, Jan 8 (Reuters) - South Sudan reduced crude oil exports in December and January as an internal strife disrupted production, industry sources familiar with the matter said on Wednesday.
The world's newest state is on the brink of a civil war after fighting erupted between the government and rebels three weeks ago, prompting oilfield operators to evacuate most of their staff.
The latest supply disruption occurred barely six months after South Sudan resumed production following a year-long halt due to a dispute with neighbouring Sudan.
Exports of heavy sweet Dar Blend will drop to 4.6 million barrels, or about 148,000 barrels per day (bpd), in January in a revised loading programme, one source said, down about 21 percent from 187,000 bpd originally planned.
Two of the seven cargoes that had been scheduled for loading in January have been deferred to February, he said.
Unipec, the trading arm of Asia's largest refiner Sinopec , had bought six cargoes while a trading firm purchased the remaining one.
It was not immediately clear what the current production for Dar Blend was, although a second source said output had dropped more than 26 percent to about 140,000 bpd.
When production was running smoothly, the country's Dar blend output was at 190,000 bpd, the source added. Official estimates put the figure at 200,000 bpd.
South Sudan exports all of its Dar Blend output as it does not have a refinery to process the crude.
Dar Blend is produced in the Upper Nile state, in Blocks 3 and 7 that are operated by the Petrodar Operating Company.
China National Petroleum Corp and Malaysia's Petronas, major shareholders of Petrodar, could not be immediately reached for comment.
Exports of Nile Blend, another Sudanese crude, have also dropped after production was shut in South Sudan's Unity state last month. The grade is also produced in Sudan where output is stable.
In a revised loading programme, two Nile Blend cargoes will load in January, down from three originally, the sources said. These include a cargo that was scheduled to load in December.
Supply cuts in South Sudan and Libya have supported Brent crude futures although physical markets, especially West African grades, remained well supplied.
CNPC, Petronas and India's ONGC Videsh hold equity stakes in Sudanese oilfields producing Nile Blend. (Additional reporting by Judy Hua in Beijing; Editing by Himani Sarkar)