The leader of a group, widely regarded as the New IRA's political wing, has said a continuation of violence is "inevitable".
In his first television interview since the murder of journalist Lyra McKee, Brian Kenna described her death as "regrettable" but denied any knowledge of the gunman.
The Police Service of Northern Ireland (PSNI) - which describes Mr Kenna's party and the New IRA as "inextricably linked" - insists violence is neither inevitable nor excusable.
Mr Kenna, a convicted IRA member who was jailed for 10 years for his part in an armed robbery, now leads Saoradh - the Irish word for 'liberation'.
He denies any overlap in the leadership of his party and the New IRA.
Ms McKee was shot dead while covering a riot in Derry in April.
Mr Kenna told Sky News: "The death of Lyra McKee was a very tragic event. It genuinely came about because of the heavy presence of the PSNI, flooding into Derry at seven o'clock in the evening, into parts of the Creggan."
"It was shocking and tragic and we're on record as saying that we regret that death very, very much," he added.
Asked if he knew the gunman, who remains at large, Mr Kenna replied: "No, I've no idea of the events of that night."
He refused to call for a ceasefire, claiming "young Irish people have always taken up arms" and "that is going to continue".
"I believe that it's inevitable," Mr Kenna said.
"Our mandate is the fact that we are an island nation, we have 32 countries, we have the right to national self-determination.
"I see no evidence of the British government announcing their intention to withdraw from Ireland at any stage - and so long as they refuse to withdraw, they will be resisted by Irish people".
"It will always happen so long as the country is artificially divided and held by force of arms, people will always strike out against that occupation," he added.
Stephen Martin, deputy chief constable of PSNI, said he had no doubt about the link between Saoradh and the New IRA.
He said: "There are people who are members of Saoradh who are members of the New IRA and some of them are in leadership positions in the New IRA."
"So there is that inextricable link between the two organisations," he added.
This year alone, the New IRA has detonated a bomb in a car outside Derry Courthouse, shot dead Ms McKee and attempted to kill police officers in booby-trap bomb attacks.
Mr Martin said: "We have seen an increase in their activity this year. Last year, there was one quite spontaneous attempt to kill police officers and this year, we've seen six incidents.
"Four of those incidents were very determined attempts to kill police officers - but violence isn't inevitable, nor is it excusable."
In his interview, Mr Kenna said that "if young people in the six counties have been more politicised and in some sense radicalised by events of recent times, then what's wrong with that?"
But Mr Martin said anyone using violence now was doing so against the expressed wishes of the majority who voted for peace.