Eight people from a little-known rebel group were arrested Saturday on suspicion of being involved in the explosion of a homemade bomb at a shopping mall that killed three people last weekend, Colombian authorities said.

The defence ministry said the arrests of four women and four men took place simultaneously in Bogota and the central city of El Espinal. The ministry said the suspects were identified using security camera footage.

Authorities said the detainees were part of a fringe group called the People's Revolutionary Movement (MRP), which has been blamed for several low-impact attacks in the capital.

Those arrested will be charged with homicide and "terrorism", national police director Jorge Nieto told journalists.

The MRP, who have only been publicly known since late 2015, are being investigated for involvement in another 14 attacks, Nieto said.

A pamphlet began circulating on social media in recent days in which the group denied any involvement in the June 17 mall bombing.

Fatal victims of the bombing were 23-year-old French woman Julie Huynh, who had been volunteering in a poor area of the city, and Colombian citizens Ana Maria Gutierrez, 27, and Lady Paola Jaimes Ovalle, 31.

Nine people were injured in the bombing, condemned by Colombian authorities and rebel leaders as a bid to disrupt the country's peace process.

The demobilisation of the leftist FARC and peace talks with the last active rebel force, the ELN, are meant to end more than half a century of violence.

No group has claimed responsibility for the mall bombing, which was the second major attack this year in the Colombian capital.

In February, the ELN claimed responsibility for a bombing at a bullring in Bogota, which killed a police officer and wounded more than 20 people.

The ELN denied any involvement in last weekend's bombing in a tweet and condemned the attack against civilians.

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The June 17 bombing occurred in the women's toilet of the Andino shopping centre in an exclusive area of Bogota. The commercial centre was packed with people buying gifts in advance of Father's Day celebrations.

Security has improved in Bogota over the past decade as police and military increased surveillance and put more armed officials on the streets.

At one time, all bags were checked at the entrance to shopping centres, but that has been vastly scaled back in recent years.

Source: News agencies