(Repeats to additional subscribers)
* Cargill suspends Ivorian cocoa purchases; U.S. backs ban
* Archer Daniels Midland carefully assessing situation
* ICE cocoa futures hit year high, Liffe at 6-month peak
* Public sector workers say received January salaries
* U.S. supports call for month-long cocoa export ban
(Adds ADM, U.S. dealer comment; adds graphic and details to lead)
By David Brough and Ange Aboa
LONDON/ABIDJAN, Jan 24 (Reuters) - Cocoa prices jumped to near their highest in 30 years on Monday as top producer Ivory Coast's Alassane Ouattara declared a month-long export ban to stop revenues reaching his rival for the country's presidency.
U.S. agribusiness giant Cargill, which typically buys about 15 percent of Ivory Coast's cocoa crop, said it had temporarily suspended cocoa bean purchases from the West African country, and the U.S. State Department backed the ban. [ID:nLDE70N1W8]
Dealers said the market was confused over the impact of Sunday's call by Ouattara -- internationally recognized as the victor of a Nov. 28 election -- given that incumbent Laurent Gbagbo controls cocoa flows out of the country.
After initially surging by more than 7 percent, cocoa futures in London and New York subsided to close 2-4 percent higher. Dealers said much of the last crop had already been exported and some additional supplies would likely find their way to market despite the ban.
"We are working with others in the industry and with the authorities to clarify and resolve the situation as quickly as possible," Cargill said in a statement.
Ouattara, who is in a hotel guarded by U.N. troops, said anyone contravening the ban, as well as other deals with Gbagbo's government, would be subject to sanctions.
But his power to enforce them was in question as Gbagbo, who has appointed his own administration and rejected pressure to step down, was likely to do everything possible to facilitate exports to generate cash to pay the military and state workers.
Archer Daniels Midland Co (ADM.N), one of the top buyers of beans in the global cocoa trade, said in a statement that it is carefully assessing the situation there and the impact of the recent European Union sanctions on its business.
"We will take appropriate actions as the situation evolves," the statement said.
A U.S. State Department spokesman said Washington supported the one-month ban, adding: "Laurent Gbagbo needs to get the message and step down."
Graphic on Ivory Coast cocoa:
Graphic on Liffe and ICE cocoa futures prices: link.reuters.com/gan67r
Reuters Insider TV: Risk of Correction Seen in Cocoa:
FACTBOX-Ivorian cocoa, plantation to port [ID:nLDE70N0VD]
TIMELINE on Ivory Coast's troubled decade [ID:nLDE70N1UM]
TAKE A LOOK-Cocoa surges on I.Coast turmoil[ID:nLDE70N16Q]
A Reuters reporter in Abidjan saw trucks laden with cocoa beans entering the port, where it was unloaded at warehouses.
Some exporters said business was continuing as usual on Monday, while others said they were unloading beans that had been previously bought but would not register them in the system for export, and would be winding down new purchases.
"We are going to buy and stock until the situation is clearer," said an Abidjan-based exporter.
Exporters estimated arrivals at ports had reached around 843,000 tonnes by Jan. 23, up about 11 percent on last year.
But, citing real time data from the port, the Ivorian cocoa sector body said on Monday the figure was higher, with 700,000 already exported and another 300,000 tonnes registered, and therefore ready for export. [ID:nLDE70N1ZQ]
Buyers swooped on the commodity as a precaution, at one point driving the key ICE second month futures contract, currently May CCc2, up to a one-year peak of $3,340 a tonne before it settled at $3,282, 3.4 percent up.
ICE second-month cocoa was within sight of its Dec. 16, 2009, peak of $3,514, the highest level in more than 30 years. Total volume on the U.S. market was nearly double the one-year average at above 26,000 lots, but down from Friday's near record high of around 44,000 lots.
Some said the rally that has driven prices up by as much as 20 percent over the past two weeks was overextended, particularly with most of the main Ivorian crop already exported.
"Whatever happens to the rest of the flow does not mean enough to keep the market up here. This will be the case as long as they are allowed to export what they have already 'declared' as ready to export," said a veteran cocoa dealer.
"Having bought a total of nearly 900,000 tonnes to date, I think that the multinationals will comply (with the ban), especially the French and U.S.A."
"IN THE DARK"
In a response to Ouattara's government, a copy of which was seen by Reuters, the Federation of Cocoa Commerce and the European Cocoa Association warned a sudden halt of cocoa and coffee exports would have "disastrous" consequences for local businesses and markets both in Ivory Coast and abroad.
Some 260 people have been killed in the crisis, which some fear could thrust the nation back into civil war.
West African regional body ECOWAS has threatened to oust Gbagbo militarily. The bloc's chair Nigeria said on Monday it wanted U.N. backing for military intervention to keep the Ivorian crisis from destabilizing the region. [ID:nLDE70N0QY]
However analysts say any such move is some time off and the priority now is squeezing Gbagbo's finances, including cocoa, which provides about $1 billion in revenues per year.
In a sign Gbagbo still has funds at his disposal, a total of eight public sector workers contacted by Reuters on Monday -- including doctors, teachers and members of the armed forces -- said they had received their full January salaries.
While Cargill's decision lent weight to Ouattara's call, some commentators were sanguine as they expected that beans would continue to flow despite the political standoff.
Romain Lathiere, a fund manager with Swiss-based Diapason Commodities Management, said: "In the end, the exporters are still going to be able to export. Cocoa will transit to Ghana, or other countries, and will still get out." ($1=.6274 Pound) (Additional reporting by Loucoumane Coulibaly in Abidjan; Nicholas Tattersall in Lagos; Anna Yukhananov in London, Charlie Dunmore in Brussels and Marcy Nicholson in New York; Washington bureau; writing by David Lewis, editing by Alden Bentley)