The AFL are concerned a soccer World Cup in Australia could affect their competition for up to two years.In a letter sent to Football Federation Australia (FFA) chief executive Ben Buckley, AFL chief executive Andrew Demetriou wrote of the league's "extreme disappointment" with the information it has received about the Cup bid.But the FFA have hit back, saying they have met with the AFL more than a dozen times in the last 20 months.An FFA spokesperson said it was "hard to understand" why the league is raising issues in the media.On Monday, Demetriou said an entire AFL season could be lost if Australia hosted the World Cup in 2018 or 2022.Demetriou sent the letter to Buckley on November 24 and the 16 club presidents have also seen a copy.In the letter, Demetriou says the AFL could have to shut down for at least 10 weeks.He also speculates about Australia hosting soccer's Confederations Cup the year before the World Cup."Therefore the FFA cannot guarantee that the impact on the AFL, clubs and their supporters will not be over two years instead of one as originally advised by the FFA," Demetriou said.The FFA have confirmed Australia would host the Confederations Cup as a warm-up for the World Cup."It has minimal impact on the other codes - but great benefit for Australia," the federation said.They also confirmed the FFA had received the AFL letter, but questioned how the league was reacting to the World Cup bid."Considering we have met 14 times with the AFL in the past 20 months, it is hard to understand why they are raising these issues in the media rather than at a meeting," an FFA spokesperson said.The AFL letter is scathing of the FFA at times and raises a series of questions about aspects of the bid."The AFL wishes to place on record its extreme disappointment with the lack of accurate and consistent information from the FFA on the implications of the World Cup on the AFL," Demetriou wrote."This lack of clear information and what appears to be indifference and frankly, reluctance to help the AFL ... is frustrating particularly given the AFL has a strong history of working with other codes and sports to accommodate major events."The FFA have confirmed their options for World Cup venues also include Etihad Stadium, but strongly denied an AFL query about whether soccer would want to take over the league's offices for the World Cup."This has not even been considered," the spokesperson said.