At least 42 people have been confirmed dead in Western Uganda following the suspected attack by a militia linked to Islamic State, Allied Democratic Forces militants on a school near the border with the Democratic Republic of Congo.

According to the Uganda People's Defense Forces Spokesperson Felix Kulayigye, the militants attacked Lubiriha Secondary at Mpondwe border in Kasese district where 39 students were killed, two residents and one security guard bringing the number to 42.

In a statement, he said, "Intelligence revealed that this attack was by suspected ADF rebels, about five in number."

Members of the Allied Democratic Forces (ADF), a Ugandan group based in eastern Congo that has pledged allegiance to Islamic State, attacked Lhubirira secondary school in Mpondwe, burning a dormitory and looting food late on Friday, police said.

Kulayigye said the school was found burning with the school food store broken into and with posho and beans taken.

Soldiers were pursuing the attackers who fled towards Virunga National Park in the Democratic Republic of Congo, police added.

Eight of those injured are seeking treatment, while three people were rescued and six were abducted, the statement said.

In April, the ADF attacked a village in the eastern Democratic Republic of Congo, killing at least 20 people. Uganda has sent troops to Congo to help fight the ADF.