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We observed with Chandra two peculiar galactic X-ray sources, 4U 1700+24 and4U 1954+319, which are suspected to have a M-type giant star as opticalcounterpart, in order to get an high-precision astrometric position for both ofthem. The peculiarity of these sources lies in the fact that these are the onlytwo cases among low-mass X-ray binaries (LMXBs), besides the confirmed case ofGX 1+4, for which the companion can possibly be a M-type giant. We found thatin both cases the field M-type giant star is indeed the counterpart of theseX-ray sources. We also determined the distance to 4U 1954+319 to be about 1.7kpc. This result suggests that a number of faint (L_X around 10^32-10^34 ergs-1) Galactic X-ray sources are `symbiotic X-ray binaries', that is, wide-orbitLMXBs composed of a compact object, most likely a neutron star, accreting fromthe wind of a M-type giant.Comment: 6 pages, 3 figures, 2 tables, accepted for publication on A&A, main  journa

M-typegiants as optical counterparts of X-ray sources 4U 1700+24 and 4U 1954+319