Comparing the different wavelengths of the DIRBE integrated surface brightness maps at positive and negative Galactic longitudes on the plane near the Galactic center, it is shown that there exists a thick dust lane (between 1.0 and 2.6 mag of absorption in K) at negative longitudes (as compared to positive ones), which follows the "standard" interstellar extinction law. A likely explanation for this effect is the existence of a thick dust lane preceding the bar. This will have to be confirmed by future infrared surveys, such as DENIS or 2MASS, that will cover negative Galactic longitudes, where a heavy extinction dust lane about 2 deg wide, close to the Galactic plane, should be seen.