BAMAKO (Reuters) - European Union observers said on Tuesday they saw irregularities but not fraud during Mali's presidential run-off, despite opposition accusations that President Ibrahim Boubacar Keita's camp cheated.
Results from Sunday's second round between Keita and opposition leader Soumaila Cisse have not yet been released but Cisse called on his supporters on Monday to challenge Keita's expected victory.
Cisse has not provided concrete evidence for his accusations and Keita has denied any wrongdoing. Cisse also said fraud marred last month's first round, but the constitutional court upheld the results.
Mali is a major concern for Western powers due to the presence of militant groups with links to al Qaeda and Islamic State.
"The vote generally took place calmly, despite security incidents in the centre and north," EU mission head Cecile Kyenge told reporters in the capital Bamako.
"Our observers did not see fraud but problems of irregularities," she said, citing threats by armed groups and a lack of communication between election officials.
In all, security issues prevented nearly 500 polling stations - about 2 percent of the total - from opening, according to Malian authorities.
EU observers did not deploy to some regions in the north and centre due to repeated attacks there by jihadist groups and ethnic militia this year that have killed hundreds of civilians, Malian troops and U.N. peacekeepers.
A Malian observer group estimated turnout for the second round at only about 27 percent of 8 million registered voters due to security fears and voter apathy.
Keita won the first round with about 41 percent of the vote despite his government's failure to slow the surging violence.
(Reporting By Tiemoko Diallo and Fadimata Kontao; Writing by Aaron Ross; Editing by Andrew Heavens)