The VISTA Variable Survey (VVV) is able to map the Galaxy at l<0 with an unpaired depth (at least 3 mag deeper than 2MASS), opening new possibilities for studying the inner structure of the Milky Way. In this paper we concentrate on the exploitation
of these data to better understand the spatial disposition and distribution of the structures present in the inner Milky Way, particularly the Long Bar and its interaction with the inner disc. The observations show the presence of a clear overdensity of stars with associated recent stellar formation that we interpret as the traces of the Long Bar, and we derive an angle for it of 41+/-5 with the Sun-Galactic centre line, touching the disc near l=27 and l=-12. The colour-magnitude diagrams presented here also show a lack of disc stars in several lines of sight, a fact that we associate with the truncation of the disc by the potential of this bar for Galactocentric radius less than 5kpc.
In this paper, we present low resolution (R=500) near-infrared spectra for selected and serendipitous sources in six inner in-plane Galactic fields, with the aim of analysing the stellar content present. From the equivalent widths of the main feature
s of the K band spectra (the NaI, CaI and CO bandheads) we have derived the metallicities of the sources by means of the empirical scale obtained by Ramirez et al. (2000) and Frogel et al. (2001) for luminous red giants. Our results show how the mean metallicity of the sample varies with Galactic longitude. We find two groups of stars, one whose [Fe/H] is similar to the values obtained for the bulge in other studies (Molla et al. 2000; Schultehis et al 2003), and a second one with a metallicity similar to that of the inner parts of the disc (Rocha-Pinto et al. 2006). The relative density of both groups of stars in our sample varies in a continuous way from the bulge to the disc. This could hint at the existence of a single component apart from the disc and bulge, running from l=7 to l=27 and able to transport disc stars inwards and bulge stars outwards, which could be the Galactic bar that has been detected in previous works as an overdensity of stars located at those galactic coordinates (Hammersley et al. 1994, 2000; Picaud et al. 2003).
