The bids for the 2018 and 2022 World Cups could be examined as part of the wider investigation into corruption allegations, the FIFA ethics investigator Michael J Garcia has said.
Lawyer Garcia declined to give further details but said there were no limitations to what he could look into.
That includes a potential investigation into what FIFA president Sepp Blatter knew about bribes paid to former FIFA officials by ISL, the organisation's now-defunct marketing partners.
A Swiss court file said there was "no question" that Blatter and other FIFA executives knew about ISL payments to former FIFA president Joao Havelange and board member Ricardo Teixeira - leading to questions about why they had taken no action on the matter for more than ten years.
"There are no limitations at all on what we will be looking at," Garcia said. "It will be determined solely by what we perceive as evidence or suggestions or reasons to look further and that will be our guiding principle - whether that is a particular World Cup or a particular person.''
His comments came after a number of allegations of misconduct were made about the 2018 and 2022 tournaments, including claims by Lord Triesman, the England 2018 bid chairman.
Garcia has launched an investigation into Mohamed Bin Hammam, who has been provisionally suspended for 90 days as a result, and has said he will look into the ISL case.
Bin Hammam had a lifetime ban for bribery overturned in court last week, but an audit of Asian Football Confederation accounts has since led to fresh allegations against the 63-year-old, who withdrew from a challenge against Blatter for the FIFA presidency after being charged last year.