The Glenshane Pass was closed for nearly three hours on Friday morning.

There are still significant elements out there in the population who seem to be determined to plunge us all back into violence

Terry Shevlin PSNI

Assistant Chief Constable Sam Kinkaid, of the north region, said he believed the UVF were responsible for the attacks.

"These incidents were organised by members of the UVF attached to south Derry," he said.

"We think the motivation may have something to do with other police operations that were being run.

"It is fair comment to say that people attached to this would not necessarily agree with the sort of political assessment that comes from other senior members of that organisation, perhaps in Belfast."

Warning

There was major traffic disruption on Thursday when a device was found on the Castledawson to Toomebridge Road and on Wednesday on the Glenshane Road.

The police also investigated reports of a number of suspicious devices in the Mid-Ulster area on Friday afternoon.

An object discovered on the Tobermore Road was declared a hoax.

The police investigated devices at the GAA club in Swatragh and at the Coleraine Road in Maghera.

Police in Coleraine also investigated reports of devices on the Garvagh to Maghera Road and the Coleraine to Garvagh Road at Moneycarry.

Traffic disruption

District commander superintendent Terry Shevlin said a warning had been received by a group purporting to be the South Londonderry Protestant Volunteer Force.

But he added: "This group is basically a cover name for a local UVF group in south Londonderry."

Local SDLP assembly member, Denis Haughey said it was a worrying development and "clear evidence of an upsurge in activity from within the loyalist paramilitaries".

"It is extremely worrying that there are still significant elements out there in the population who seem to be determined to plunge us all back into violence," he said.

Police are warning members of the public to call them immediately if they discover any suspect objects.