Efforts to establish a mammoth free trade deal between the European Union and the United States are falling short, the top US negotiator warned Friday, as the two sides wrapped up their eighth round of talks in Brussels, dpa reported. Once concluded, the Transatlantic Trade and Investment Partnership (TTIP) will create the world's largest free trade zone, with both parties hoping for an economic boost. But progress has been slow, while consumer groups on both sides of the Atlantic have expressed fears that the deal could lead to a watering down of standards and a loss of regulatory control. The top trade officials in Brussels and Washington had both expressed hope that this week's talks would mark a "fresh start," following the appointment of a new EU executive and mid-term elections in the United States last year. However, US chief negotiator Dan Mullaney said greater efforts are needed. "This week's round was constructive, but we do need to see more, further concrete progress ... if we are to turn this fresh start into a reality," Mullaney warned.