Flint was due to appear on a panel at a conference on Thursday but the panel's moderator, Louis Taylor, director general of the Department for International trade said Flint had to meet with Prince Mohammed instead. An HSBC spokeswoman declined to comment.
One of the sources said Winters also attended the meeting.
Saudi Arabia is looking at listing part of its state oil company Saudi Aramco and banks are vying to win formal mandates for the initial public offering.
(Reporting by Dasha Afanasieva and Lawrence White. Editing by Jane Merriman)
