Questions are being asked about the circumstances surrounding the killing of Mark Duggan as police launch an investigation into the riots sparked by his death in Tottenham.

The Independent Police Complaints Commission (IPCC) said it was investigating what happened on Thursday evening in north London's Tottenham, when Duggan was shot by armed police.

The Guardian and Daily Telegraph cited sources as saying a bullet lodged into a police radio at the scene where the 29-year-old father of four was shot could have been issued by the police, according to initial ballistics tests.

"We await further forensic analysis to enable us to have a fuller and more comprehensive account of what shots were discharged, the sequence of events and what exactly happened," the commission said in a statement. But it said it wouldn't comment on the latest claims until all ballistics and forensic tests were complete.

The IPCC would not comment on the reports.

Police are also probing the events of Saturday night, when a peaceful march turned into one of the worst riots in Britain for many years. Hooded and masked youths threw bottles and petrol bombs at police and buildings and vehicles, setting a building, a bus and cars alight.

Tension remained high across London on Sunday with over 100 new arrests across the capital following the riots overnight, which left 26 police officers injured and saw 55 people arrested.

On Monday morning London's deputy mayor Kit Malthouse said the investigation into Duggan's death would take some time.

"The investigation into Mark Duggan's sad death is for the Independent Police Complaints Commission. It is not a Met Police investigation.

"Whenever a firearm is discharged in the UK, the IPCC is involved in the investigation into that shooting, whether it is fatal or not and so they are handling the investigation and I think there has been frankly a bit of confusion in people's minds and conflation if you like between the police and the IPCC and we need to look and disaggregate that.

"But at the same time one of the things that Mr Duggan deserves, is a good and thorough investigation. And that takes a little bit of time, and whether that community had been told that is something we need to look at", he told the BBC this morning.

But he said there was no excuse for the behaviour. "Somehow they managed to get in amongst that crowd and caused this kind of trouble, and I think we have to be careful, particularly in the media, not to create some kind of atmosphere of excuse for this kind of behaviour, there was no excuse for the behaviour if the last two nights, we have to make that clear and bring those who perpetrated it to justice."

Meanwhile the family of Mark Duggan told Sky News they do not condone the rioting over his death.

His brother Shaun Hall told the broadcaster: "We're not condoning any kind of actions like that at all. It seems to be the press who are generally saying that it is linked to my brother.

"OK, some questions were supposed to have been answered, they weren't answered, therefore there was a domino effect from that, we don't condone that at all."