The fuel was recovered as part of an operation targeting fraud by HM Revenue & Customs on Thursday.
HMRC officers visited two retail sites in Newtownabbey and Lurgan where they seized 6,500 litres of red diesel and removed four forecourt pumps.
Officers removed two diesel forecourt pumps and an over ground fuel storage tank from a third retail site, suspected to be selling laundered fuel, in the Glarryford area.
Three private vehicles were seized and restored during the operation.
John Whiting, assistant director, Criminal Investigation, HMRC, said: "Retailers who knowingly sell red diesel to road users will not only face seizure and removal of fuel and equipment from their premises, but also risk losing their licence to trade in red diesel.
"Selling illicit fuel creates an unfair playing field and seriously undercuts legitimate traders who should be able to operate without the threat of unfair competition.
"Anyone with information on fuel misuse or suspicious activities can contact the Customs' hotline on 0800 59 5000."