Gardaí have discovered two cannabis grow-houses in the past 48 hours - one in Co Waterford and another in Co Monaghan.

Two Vietnamese men, aged 32 and 43 years, were arrested on Thursday at an industrial premises in Waterford Airport Business Park.

During the operation, more than 1,000 cannabis plants at various stages of growth were found. They have an estimated street value of €800,000.

It was part of an intelligence-led operation by officers from the Tramore Drugs Unit, assisted by the Armed Support Unit in Waterford.

The two men are being detained at Tramore Garda Station under Section 2 of the Criminal Justice Act.

In Monaghan, a cannabis grow-house in the Ballybay area was discovered. Around 100 cannabis plants were found in a wooded area in Larragh.

It is believed the drugs are worth around €50,000. Nobody has been arrested so far in connection with the find.

A number of cannabis grow-houses have been targeted by gardaí in recent weeks. On Wednesday another was discovered by gardaí in Co Leitrim.

It was found during a search of a rented property in the Manorhamilton area.

Gardaí seized cannabis cultivation equipment, along with 50 fully mature cannabis plants, 90 plants in the early stages of growth and a kilogramme of processed cannabis herb.

Two Lithuanian nationals - aged 22 and 49 - were arrested during that garda operation.

Last month, gardaí discovered a cannabis grow-house in Dublin. Officers from the South Eastern Region and the Garda National Drugs & Organised Crime Bureau carried out a number of searches in Dublin and Wexford targeting an organised crime group.

They found a cannabis cultivation unit when they searched commercial premises in the north inner city area of Dublin.

There were more than 800 cannabis plants, with an estimated value of €640,000, seized. They also arrested four people at the scene.

Officers carried out more searches in Co Wexford where a further five arrests were made.

The nine people arrested are being held at Garda Stations in Dublin and Wexford and they include six Portuguese men, a British man, and a man and woman from Ireland. They range in age from 17 to 45 years.