DUBLIN (AFP) - A "terrorist hide" discovered in Northern Ireland containing land mines, pipe-bombs and other weaponry is "one of the most significant seizures in recent years", police in the British-ruled province said on Tuesday.

The cache, which is believed to have been assembled by dissident republicans dedicated to creating a united Ireland by force, was discovered on Saturday evening by two people walking in Capanagh Forest near the port of Larne, around 50km north of Belfast.

In a statement, Detective Superintendent Kevin Geddes of the Serious Crime Branch said the find had undoubtedly saved lives as a number of the devices were ready for deployment.

"The fact that an Explosively Formed Projectile was recovered which has an armour-piercing capability means that one of our main lines of enquiry will focus on dissident republican terrorists," he said.

"All these components will now be subjected to rigorous forensic testing in an effort to provide additional lines of enquiry."

The officer also said the force was investigating apparent similarities with another stash found nearby in 2015.

"This significant find is v good news. Terrorists will not now be able to use potentially lethal items," said Northern Ireland Secretary of State Theresa Villiers in a statement on Twitter.

Northern Ireland security forces dealt with an average of a bomb attack every week over the past year - an increase of 44 per cent over the previous year, police figures released last week showed.

Separately, the British government increased the threat level of an attack from Northern Ireland in Scotland, England and Wales from "moderate" to "substantial" this month.

The rating means it now considers there is "a strong possibility" that an attack will take place.

The threat to Northern Ireland itself, which was riven by three decades of conflict and where there are still strong sectarian tensions despite the signing of a peace agreement in 1998, remains severe.