* Sudan poll counting chaotic, open to manipulation
* Observers concerned at intimidation of poll staff
* Urges election commission to review disputed results
KHARTOUM, May 10 (Reuters) - Vote-counting after Sudan’s April elections was chaotic and open to manipulation, raising concerns over the accuracy of the results, an international observer mission said on Monday.
The five-day vote was Sudan’s first multi-party election in 24 years but was undermined by boycotts and claims of fraud by the opposition and observer groups said the voting had failed to meet international standards.
"Sudan’s vote tabulation process was highly chaotic, non- transparent and vulnerable to electoral manipulation," the Carter Center said.
"The Center is concerned about the accuracy of the preliminary results by the National Elections Commission (NEC)," the U.S.-based group said in a statement.
Sudanese President Omar Hassan al-Bashir, the only sitting head of state wanted for war crimes by the International Criminal Court, was confirmed in office by the vote.
Salva Kiir was re-elected president of the semi-autonomous south, which will vote in a referendum on independence early next year.
Although parliamentary results have not yet been fully released, Bashir’s ruling National Congress Party (NCP) and its allies look to have won most of the seats in the north.
Kiir’s Sudan People’s Liberation Movement (SPLM) saw sweeping wins in the south.
The few participating northern opposition parties said they only won two seats in the 450-seat national parliament. The massive margins by which the NCP candidates won were evidence of fraud, they said. The NCP denies any irregularities, saying the opposition were weak and unprepared.
The southern opposition also complained of intimidation, harassment and manipulation of results, which Kiir promised to investigate.
The Carter Center, led by former U.S. President Jimmy Carter, deployed about 70 election observers. It expressed concern that results systems with inbuilt security measures were bypassed during the counting.
"Observers reported officials tabulating results on loose sheets of paper and crudely constructed forms in most states," it said. "The unplanned manual tabulation has undermined the accuracy of the results process."
The Carter Center said that in seven states its observers were stopped from witnessing the counting. It also noted numerous polling stations with 100 percent turnout, or where 100 percent of votes were cast for one candidate or one party, particularly in east and south Sudan.
In the south, Bashir fared badly, with just 1.6 percent of the vote in Warrap state. In the east, he got extremely high votes — up to 95.4 percent in Red Sea state.
The Carter Center urged the National Elections Commission to review dubious results.
"Observers noted serious incidents of intimidation, arbitrary detention and violence against election management staff, party agents and citizens," the statement said.
"The elections in Unity State suffered from large-scale intimidation, violence, flaws in administration, and indications of manipulation," the statement said, adding this may have affected the overall result in the oil-producing state.
The Atlanta-based Carter Center promotes human rights across the globe and has monitored elections in many countries. (Reporting by Opheera McDoom; Editing by Giles Elgood)