(CNN) -- Three Russian pilots working for a Sudanese aviation company have been abducted in the Darfur region, officials said Monday.
The pilots were abducted Sunday in Nyala, the capital of the southern Darfur region, said Chris Cycmanick, spokesman for the African Union-United Nations Mission in Darfur.
Thirteen people have been abducted in Darfur this year, Cycmanick said. Ten have been released; three currently in custody are those who were abducted Sunday.
The mission had seven of its personnel taken hostage earlier this year, but all were safely released, Cycmanick said.
The United Nations has extended its mission in Darfur for another year, despite a report released at the end of July that painted a grim picture of the security situation there. It found that violence in the region has increased over the previous year.
May 2010 was the deadliest month in Darfur since the U.N. mission deployed there in 2007.
According to U.N. statistics, as many as 300,000 people are believed to have died, and at least 2.5 million have been displaced from their homes in Darfur since fighting broke out between the government, the government-allied Janjaweed militia and other armed rebel groups in 2003.
The conflict has been marked by widespread atrocities, including the murders of civilians and the rapes of women and girls.