Two men from Northern Ireland have been arrested in the Republic as part of an operation against illegal diesel laundering. The men, aged 33 and 34, were arrested at commercial premises in Glaslough, County Monaghan on Monday night. Customs officers recovered a tanker delivering 40,000 litres of diesel to the premises. The facility could have deprived the Republic\'s exchequer of up to 4m euros (£3.4m) a year in lost revenue. After following the tanker, customs officers, supported by armed gardai, raided the illegal diesel laundering plant. Inside they found an underground tank into which the fuel, originally intended for agricultural use, is pumped with a bleaching agent to remove the dye. When the dye is removed, the fuel is sold on as conventional road diesel, making a significant profit for the launderers.