Tanzania has arrested 20 suspected army deserters from the Democratic Republic of Congo (DRC) after they illegally entered the western port town of Kigoma, the Tanzanian army said on Tuesday.

The soldiers arrived in Tanzania on November 5 in full military uniform with heavy weapons without following proper procedures, army spokesman Kapambale Mgawe told Reuters.

Unconfirmed reports from the DRC say the soldiers might have deserted from the Congolese army some six months ago, Mgawe said.

He said the suspects claimed they were chasing a group of nine unarmed rebels who arrived in Tanzania on November 3 and were also arrested by the Tanzanian police.

The Congolese soldiers were led by a lieutenant colonel ... it is baffling that such a ranking military officer and his men could have entered Tanzania in full military battle gear without seeking prior permission from us.

The soldiers were armed with sub-machineguns, pistols, rocket-propelled grenades, plus anti-aircraft and anti-tank weapons, he said.

While open conflict between the army in eastern Congo and Tutsi-led CNDP rebels has ended, the region bordering Tanzania, Burundi and Rwanda is still dogged by violence.

The Congolese army is fighting Rwandan Hutu FDLR rebels and several other rebel groups. There have also been clashes between factions within the army, and the restructuring of regiments in the east has led to desertions.

Mgawe said the 20 Congolese soldiers arrived in Tanzania by boat from Congo via Lake Tanganyika. He said the Tanzanian authorities were communicating with their DRC counterparts to establish the identities of the detainees.

We are questioning them to establish if they are indeed deserters from the DRC army and if they have any connection to the nine unarmed Congolese men.

Tanzania's Kigoma region also hosts more than 40,000 refugees from Congo's conflict zones.