KINSHASA (AFP) - Gangs of youths angered by the arrest and alleged mistreatment in northern India of 21 Congolese students have threatened Indian shop-owners in Kinshasa, witnesses said.

A woman running a foreign exchange booth in the La Gombe neighbourhood of the Democratic Republic of Congo's capital told AFP that several shop-owners had received threats on Wednesday.

Congolese police sent reinforcements to protect the shops but there was no visible security deployment on Thursday.

According to newspapers in Kinshasa, 21 young Congolese nationals studying computer science in the northwestern Indian city of Jalandhar were arrested following scuffles and locals at the weekend.

Allegations on social media that the students were reacting to a racist attack and were subsequently subjected to police brutality prompted gangs to take to the streets of Kinshasa.

India's ambassador to the central African country, Manohar Ram, told Congolese reporters on Wednesday that 17 of the detained students had already been released and that the other four would be soon.