The Garda Commissioner has said he feels confident with the progress that is being made in investigating recent violent incidents in the border region.

Drew Harris said he did not accept that the area was "lawless" and said gardaí were involved in a difficult and complex investigation.

He was speaking after addressing the Cabinet sub-committee on security with the Taoiseach this afternoon.

Mr Harris said "at this moment" there did not seem to be a "causal link" between recent incidents, and he did not believe there was a single criminal gang behind them.

It follows the arson attacks at the home of the Sinn Féin TD Martin Kenny and Emyvale Garda Station in Co Monaghan, and the continuing threats to and attacks on Quinn Industrial Holdings executives.

Minister for Justice Charlie Flanagan said every effort was being made to bring to justice those responsible for what he called recent "unacceptable acts of violence".

The minister said there was an "unprecedented level of coordination and co-operation" in relation to the investigation into threats to directors of Quinn Industrial Holdings.

In relation to intimidating posters currently displayed in Co Cavan, the Garda Commissioner said these would be removed even if this required specialist assistance.

Earlier, Taoiseach Leo Varadkar said the Government had increased garda resources along the border and would do so again.

He said recent "lawlessness" in the region was being taken with the "utmost seriousness".

Mr Varadkar said "the rule of law" must prevail, that the Government had increased garda resources along the border and would do so again.

He said he wanted to hear from the commissioner on what more they could do to bring the perpetrators of these crimes to justice.

He also asked people in border communities not to be afraid to come forward, to give gardaí the information and "we will make sure those involved will be brought to justice".

It comes after the CEO of Quinn Industrial Holdings said the latest threats against its directors are "being taken very seriously at the highest level".

The threat, delivered to the Irish News, was conveyed to Quinn directors on Monday night by gardaí. In the threat, which was typed, directors were told that it was their final warning.

Speaking on RTÉ's Morning Ireland, Liam McCaffrey said the PSNI and gardaí were monitoring the homes and places of work of QIH's directors.

Meanwhile, the Garda Representative Association said it was a "major challenge" to police along the border "given the resources available".

Speaking on RTÉ's News at One, GRA representative James Morrisroe said that since 2011 the number of gardaí in the Ballyconnell district station has reduced by nearly two-thirds, due to the downgrading of Ballyconnell from a district headquarters.

He described the recent allocation of the armed response unit to the area as a "welcome first step", but said there remains a "deficit of resources in the border area".

Mr Morrisroe said the lack of patrol cars in the Cavan-Monaghan division leaves it impossible for gardaí to perform their duties along the border.

He said: "There is a deficit of patrol cars in the Cavan-Monaghan division. By the end of the year there will be a deficit of ten patrol cars. How can we effectively police a vast rural border area without the basic tools to do our jobs?

"It is simply not possible for frontline officers to do their jobs without the resources and tools to do so."

Additional reporting Paul Reynolds