A fire which burned for four days at a landfill site in Thessaloniki, sending thick black smoke over the city, was under control yesterday after a long effort by firefighters, officials said. Since Thursday, the fire service had been battling to bring the blaze at the Tagarades dump under control. Efforts had been hampered by the extreme heat as the fire burned plastic items in the garbage. A water-dropping helicopter helped quell the blaze yesterday so firefighters could move in and extinguish it. It is not clear what caused the fire, which is thought to have released toxic fumes into the air. The fire also caused sections of the earthen walls of a sewage-collection basin next to the dump to break. This led to sludge flowing into some nearby houses. Authorities are due to begin the cleanup operation today. «It is only a small indication of what can happen if we do not move to an integrated waste management system, as we have been talking about for years,» said the head of the local authority, Yiannis Zournas.