Anti-corruption advisers appointed by FIFA say it's important to give "a convincing and transparent answer" to allegations about Qatar's selection as 2022 World Cup host.

The advisory panel chaired by Swiss law professor Mark Pieth says FIFA's ethics committee investigating the 2018-2022 World Cup hosting decisions "should not rest until there is a conclusive answer."

Pieth's independent governance committee supports ethics prosecutor Michael Garcia in helping "fearlessly to investigate allegations of corruption at the heart of FIFA."

The comments were published on Wednesday in Pieth's 15-page final report to the FIFA executive committee summarizing the panel's work. Some members of FIFA's board, which voted for Qatar and Russia as World Cup hosts, wanted to remove Garcia.

Pieth writes that FIFA officials must "unconditionally cooperate with Mr. Garcia's investigation."