KHARTOUM (BLOOMBERG) - Sudanese President Omar al-Bashir was sworn in for another five-year term after a landslide victory in April's elections extended his quarter-century rule over the North African nation.

"I will be president to all Sudanese people, whether they voted for me or they boycotted these elections," Mr Bashir said Tuesday after taking the oath at the national parliament in Omdurman, the twin city of the capital, Khartoum, in a ceremony broadcast on state television.

Kenyan President Uhuru Kenyatta, Egypt's Abdel-Fattah El-Sisi and Zimbabwe's Robert Mugabe were among those attending.

Mr Bashir, who took power in a 1989 coup, has been indicted by the International Criminal Court for alleged crimes against humanity during the decade-long conflict in Sudan's western region of Darfur.

He was re-elected in 2010 in a vote whose credibility was questioned by international observers including the European Union.

The 71-year-old won 94 per cent of the vote in mid-April polls that the main opposition parties boycotted.

Sudan's electoral board said the turnout was 46.4 per cent, higher than the 30 per cent to 35 per cent estimated by an African Union observer mission.