In 1993, the Fatah-controlled PLO signed the Oslo Accords officially recognizing Israel.
This week Mohammed Dahlan, a senior Fatah figure, insisted that Fatah as an organization never recognized Israel. You can't blame him. The majority of the Palestinian population doesn't consider Israel legitimate and in fact wants to see it destroyed. It's in his interest to generally follow the will of his people. He is in a pissing contest with Hamas over who can be more anti-Israel.
Remember these are the "moderates."