  LSI +61 303 is one of the most interesting high-mass X-ray binaries owing to
its spatially resolved radio emission and its TeV emission, generally
attributed to non-thermal particles in an accretion-powered relativistic jet or
in the termination shock of the relativistic wind of a young pulsar. Also, the
nature of the compact object is still debated. Only LS 5039 and PSR B1259-63
(which hosts a non-accreting millisecond pulsar) have similar characteristics.
We study the X-ray emission from LSI +61 303 covering both short-term and
orbital variability. We also investigate the source spectral properties in the
soft X-ray (0.3-10 keV) energy range. 25 snapshot observations of LSI +61 303
have been collected in 2006 with the XRT instrument on-board the Swift
satellite over a period of four months, corresponding to about five orbital
cycles. Since individual data sets have too few counts for a meaningful
spectral analysis, we extracted a cumulative spectrum. The count rate folded at
the orbital phase shows a clear modulation pattern at the 26.5 days period and
suggests that the X-ray peak occurs around phase 0.65. Moreover, the X-ray
emission appears to be variable on a timescale of ~1 ks. The cumulative
spectrum is well described by an absorbed power-law model, with hydrogen column
density Nh=(5.7+/-0.3)E+21 cm^-2 and photon index 1.78+/-0.05. No accretion
disk signatures, such as an iron line, are found in the spectrum.
