The Allied Democratic Forces -- which the Islamic State group claims as its Central African offshoot -- is accused of slaughtering thousands of Congolese civilians and carrying out bombings in Uganda.

An "estimated 20-30 ADF fighters last night crossed River Semliki... Our intelligence got wind of them and they were intercepted," Brigadier-General Felix Kulayigye, spokesman for the Ugandan military, said in a statement.

"A fight is on to decisively deal with the group," he said, adding that 11 rebels had been killed while eight others had been taken into custody.

"Operation is ongoing," he said.

The ADF is among the most violent of more than 120 armed groups active in the DRC's volatile east.

Uganda was hit by a series of bombings in October and November last year that killed five people and injured dozens, with the authorities blaming a "domestic terror group" with ties to the ADF for the blasts.

Following the attacks, Uganda deployed forces and launched air and artillery strikes in the DRC against the ADF, after Kinshasa gave Kampala approval to pursue the militants on its soil.

Last year, the United States placed the ADF on its list of "terrorist" organisations linked to IS.

Uganda has also blamed the group for a foiled bomb attack in August 2021 on the funeral of an army commander who led a major offensive against Al-Shabaab militants in Somalia.

The DRC has witnessed fierce fighting in recent months between Congolese troops and the M23 rebel group.

Uganda announced last month that it would deploy around 1,000 soldiers in the eastern DRC as part of a joint regional force to quell the violence.