At least 25 people have been killed at a school in western Uganda by rebels linked to the Islamic State group.

A further eight people remain in a critical condition after the attack on Lhubiriha secondary school in Mpondwe.

Police say the attack on Friday was carried out by the Allied Democratic Forces (ADF) - a Ugandan group based in the Democratic Republic of Congo (DRC).

Soldiers are pursuing the group who fled towards Virunga National park in the DRC, police added.

"So far 25 bodies have been recovered from the school and transferred to Bwera Hospital", national police spokesperson Fred Enanga said in a statement on Saturday. 

A dormitory at the school was burnt and a food store was looted during Friday night's attack, he added. 

The attackers are also thought to have detonated bombs in the region.

The death toll might be as high as 40, with members of the wider community possibly among the dead.

Dozens of people are feared to have been abducted and a number of students are still unaccounted for. 

"Our forces are pursuing the enemy to rescue those abducted and destroy this group," defence spokesperson Felix Kulayigye said on Twitter.

The attackers have fled towards Virunga National park - Africa's oldest and largest national park which is home to rare species, including mountain gorillas. 

Militias including the ADF also use the vast expanse, which borders Uganda and Rwanda, as a hideout. 

Uganda and the DRC have held joint military operations in the east Congo to prevent attacks by the ADF. 

The attack on the school, located less than two kilometres (1.25 miles) from Uganda's border with the DRC, is the first such attack on a Ugandan school for many years.

In June 1998, 80 students were burnt to death in their dormitories in an ADF attack on Kichwamba Technical Institute near the border of DRC. More than 100 students were abducted.

The ADF was created in eastern Uganda in the 1990s and took up arms against long-serving President, Yoweri Museveni, alleging government persecution of Muslims. 

After its defeat by the Ugandan army in 2001, it relocated to North Kivu province in the DRC. 

The group's principal founder, Jamil Makulu, was arrested in Tanzania in 2015 and is in custody in a Ugandan prison. 

ADF rebels have been operating from inside the DRC for the past two decades. 

In 2021, suicide bombings in Uganda's capital Kampala and other parts of the country were blamed on the ADF.