Sudan is voting in elections expected to be won by its war-crimes-indicted President Omar al-Bashir after the main opposition called for a boycott.
Small queues formed at polling stations, with voters saying the elections guaranteed stability.
The opposition and Western powers said the polls lacked credibility because of political repression.
Mr Bashir has ruled Sudan since 1989, and is charged by the International Criminal Court (ICC) with genocide.
The 71-year-old president denies the charges, which arose from the conflict in Darfur.
The African Union (AU) has rejected the ICC’s attempts to have him arrested, arguing that Mr Bashir enjoys presidential immunity and therefore cannot be tried while in office.
• President Omar al-Bashir is up against 15 little-known candidates
• 44 parties are taking part in the parliamentary poll
• US relations – lifting economic sanctions and getting the country removed from the list of state sponsors of terrorism
• Securing peace – there is fighting in Darfur, South Kordofan and Blue Nile
• Economy – when the South Sudan seceded, the country lost most of its vital oil revenues
Will Bashir be snubbed by his people?
How Sudan’s election works
The BBC’s James Copnall reports from Khartoum that there is a large crowd where Mr Bashir is voting, but most of them are journalists and security personnel.
Ahmed Sulieman, a university professor, said he was voting as it was the only way to guarantee a peaceful transfer of power.
“Many countries are suffering amid power struggles,” Mr Sulieman told Associated Press news agency.
“I am here for the sake of stability and safety,” he added.
Mr Bashir is being challenged by 15 little-known candidates, after the main opposition parties denounced the polls as a sham.
The UK, US and Norway have said in a statement that “an environment conducive to participatory and credible elections does not exist” in Sudan.
The three countries form a troika which has been trying to resolve differences between the government and opposition.