Thousands of Rwandans and well-wishers Wednesday afternoon gathered at the gates of the United Kingdom’s High Commission in Kacyiru, Kigali to protest against the recent arrest of the head of the National Intelligence and Security Service (NISS).

Lt Gen Karenzi Karake, who was in London on official duty, was on Saturday barred by the UK immigration officials from boarding a flight back home, over an indictment issued by a Spanish judge.

The demonstrators braved a scorching sun as they chanted songs demanding the release of Karake at the UK High Commission – a day after news about the arrest filtered through.

They demanded to speak to the High Commissioner William Gelling who came out an hour later to listen to the protesters’ grievances.

"We are here to demand for an immediate release of General Karenzi Karake who was illegally detained by the UK authorities over unsubstantiated claims. Rather than going for those who committed Genocide you are instead going for men who stopped it,” said one of the demonstrators, Herbert Muhire, as he delivered the protesters’ message to the UK envoy.

Another protester, Apollo Munanura, told Gelling that; "We strongly believe that Gen Karenzi has no case to answer in the UK and we are going to camp here until he is released.”

The two were cheered by fellow demonstrators who had placards carrying several statements showing solidarity with Gen Karake.

"I have received your message, I understand your frustrations. His arrest was on legal obligations based on the Spanish indictments. UK is a close partner and maintains a good relationship with Rwanda,” Gelling told the demonstrators.

By press time, more people were still coming to the embassy to join in the protests.

Karenzi’s arrest has been linked to a highly controversial 2008 indictment by a Spanish judge targeting the intelligence chief and 39 other high-ranking current and former Rwandan government officials.

Kigali has described both the arrest and the indictment itself as "outrageous” while researchers and genocide scholars have linked the two to the sympathizers of the regime that carried out the 1994 Genocide against the Tutsi which claimed more than a million lives.

A 2009 UN panel of experts said Judge Fernando Andreu Merelles’ indictment had been sponsored by two Spanish NGOs that had funded FDLR, the DR Congo-based militia largely blamed for the 1994 Genocide and which continues to defy international efforts to have it disarmed.