* Opposition accusations of ballot-tampering, intimidation
* Boycotts in north undermine election's credibility
JUBA, Sudan, April 21 (Reuters) - Opposition groups in south Sudan accused soldiers and officials on Wednesday of tampering with ballots and intimidating polling agents during vote counting, the latest accusations to mar landmark elections.
Sudan is holding its first open elections in 24 years as part of a 2005 peace deal which ended more than two decades of north-south civil war. But a wave of boycotts in the north tainted the vote's credibility there.
Analysts say the polls are a test of democracy in Africa's largest nation, particularly in its oil-producing south which is preparing for a referendum in January 2011 on whether to declare independence from the north.
Six independent and opposition candidates from different parts of the south told Reuters their supporters had been intimidated by southern soldiers or officials from the south's dominant Sudan People's Liberation Movement (SPLM) during last week's five-day voting period and the vote counting.
Albino Akol Akol of the opposition United Democratic Salvation Front party said nine ballot boxes from seven polling stations were stolen and are still missing in his constituency.
"These are not elections, they are a mockery," he said. Akol said in five voting centres in Northern Bahr el Ghazal's Malwal area the army lashed agents and then managed the polling stations alone.
South Sudan's army (SPLA) denied interfering in any part of the polling, saying opposition candidates were complaining to cover up for their poor performance in the poll.
"This is just to justify their defeats ... There's no evidence of this," army spokesman Kuol Diem Kuol said.
SPLM official Yasir Arman also dismissed the accusations.
The 2005 peace deal created a semi-autonomous southern government and allowed the region to keep its own army. The former rebel SPLM is expected to win most votes.
REPORTS OF INTIMIDATION
Southern opposition and independent candidates from constituencies in the states of Unity, Eastern Equatoria, Upper Nile and close to the southern capital Juba, said security forces had chased their agents away during vote counting.
Sarah Nyanath, an independent vying for Upper Nile governor, said in the state's Logushuk area a government official dismissed all the polling agents from one station prior to counting and then added 732 votes to the ballot boxes.
A south Sudan elections official could not confirm that report but said many staff members had complained of harassment.
A British-led team of observers said on Wednesday it had recorded intimidation in the south. But it said overall in the mostly urban areas they were able to access, the elections were handled professionally by security forces.
"Most of the overt, if not all the overt intimidation we saw was in the south, mostly by the SPLA," Paul Moorcraft, head of the 50-strong mission, said.
The White House this week said the elections were beset by "serious irregularities" across the country.
The announcement of official results from Sudan's elections, scheduled for Tuesday, has been held up by technical problems and delays in vote counting in the south.
The few opposition parties which participated in the north have all rejected the poll results, alleging ballot-rigging.
Early results in the north suggest an overwhelming win for President Omar Hassan al-Bashir, wanted by the International Criminal Court to face charges of war crimes in Darfur. (Additional reporting by Andrew Heavens and Opheera McDoom in Khartoum; Editing by Charles Dick)
Our Standards: The Thomson Reuters Trust Principles.