First of all, I am also not a lawyer, nor any kind of expert in trademark law in any jurisdiction. For a definitive answer, you really need to consult a local intellectual property lawyer.
That said, according to that fount of all legal knowledge on the Internet, Wikipedia, you should generally be safe, at least under U.S. law, as long as you're only using the competitor's name to identify them, and not in any way that could imply endorsement or generate confusion between your brands:
"Fair use may be asserted on two grounds, either that the alleged infringer is using the mark to describe accurately an aspect of its products, or that the alleged infringer is using the mark to identify the mark owner. [...]
An example of the second type is that Audi can run advertisements saying that a trade publication has rated an Audi model higher than a BMW model, since they are only using "BMW" to identify the competitor. In a related sense, an auto mechanic can truthfully advertise that he services Volkswagens, and a former Playboy Playmate of the Year can identify herself as such on her website."
(The superscript numbers are references to prior court cases; specifically, Volkswagenwerk Aktiengesellschaft v. Church, 411 F.2d 350, 352 (9th Cir. 1969) and Playboy Enterprises, Inc. v. Welles, 279 F.3d 796 (9th Cir. 2002).)
Generally, similar provisions are likely to exist in other parts of the world, too, since it would be highly impractical if one could not legally refer to a company or a brand by the name they use themselves. However, the scope of these "fair use" provisions may vary, in particular when it comes to use of competitors' trade marks in promotional material. As I noted earlier, to be sure, you really should ask a lawyer.