  The study of the observational properties of uncommonly long bursts from low
luminosity sources with extended decay times up to several tens of minutes is
important when investigating the transition from a hydrogen-rich bursting
regime to a pure helium regime and from helium burning to carbon burning as
predicted by current burst theories. IGR J17254-3257 is a recently discovered
X-ray burster of which only two bursts have been recorded: an ordinary short
type I X-ray burst, and a 15 min long burst. An upper limit to its distance is
estimated to about 14.5 kpc. The broad-band spectrum of the persistent emission
in the 0.3-100 keV energy band obtained using contemporaneous INTEGRAL and
XMM-Newton data indicates a bolometric flux of 1.1x10^-10 erg/cm2/s
corresponding, at the canonical distance of 8 kpc, to a luminosity about
8.4x10^35 erg/s between 0.1-100 keV, which translates to a mean accretion rate
of about 7x10^-11 solar masses per year. The low X-ray persistent luminosity of
IGR J17254-3257 seems to indicate the source may be in a state of low accretion
rate usually associated with a hard spectrum in the X-ray range. The nuclear
burning regime may be intermediate between pure He and mixed H/He burning. The
long burst is the result of the accumulation of a thick He layer, while the
short one is a prematurate H-triggered He burning burst at a slightly lower
accretion rate.
