The trial of 13 men accused of taking part in the 2010 Shebab bombings, which killed 76 people in Uganda's capital Kampala, resumed on Monday without the lead prosecutor, who was murdered in March.

Joan Kagezi, Uganda's acting assistant director of public prosecution, was killed by men on a motorbike in front of three of her children. Police are still hunting for the killers and have made several arrests.

Uganda said Saturday it was boosting security measures following fresh threats against the east African nation by Somalia's al-Qaida-linked Shebab rebels.

A statement by police said a new video purportedly from the Islamists and urging attacks in Uganda and Burundi -- nations that both contribute troops to the African Union's AMISOM force in Somalia -- has been circulated online.

The trial of 13 men accused of involvement in twin bomb attacks that killed 76 people in Uganda nearly five years ago finally got under way on Tuesday.

The July 2010 bombings targeted football fans watching the World Cup final between the Netherlands and Spain at a restaurant and a rugby club in the capital, Kampala. Somalia's Al-Qaida-affiliated Shebab militants claimed responsibility for the strikes, the region's worst attacks in more than a decade.

Uganda has arrested a Belgian citizen of Rwandan origin wanted by a court in his adopted homeland for involvement in the 1994 genocide, police said Friday.

Thaddee Kwitonda, 51, was detained in Kampala on Thursday after police tracked his movements for several months, police spokesman Asuman Mugenyi told AFP.

A team of Ugandan and French paleontologists announced Tuesday they had found a 20-million-year-old ape skull in northeastern Uganda, saying it could shed light on the region's evolutionary history.

"This is the first time that the complete skull of an ape of this age has been found ... it is a highly important fossil and it will certainly put Uganda on the map in terms of the scientific world," Martin Pickford, a paleontologist from the College de France in Paris, told journalists in Kampala.