  We present spectral and temporal results from INTEGRAL long-term monitoring
of the unidentified X-ray source IGR J17354-3255. We show that it is a weak
persistent hard X-ray source spending a major fraction of the time in an
out-of-outburst state with average 18-60 keV X-ray flux of about 1.1 mCrab,
occasionally interspersed with fast X-ray flares (duration from a few hours to
a few days) with a dynamic range as high as 200. From archival Swift/XRT
observations, we also show that the dynamic range from non-detection to highest
level of measured X-ray activity is >300. Our IBIS timing analysis strongly
confirms the 8.4 days orbital period previously detected with Swift/BAT, in
addition we show that the shape of the orbital profile is rather smooth and
appears to be dominated by low level X-ray emission rather than by bright
outbursts, the measured degree of outburst recurrence is about 25 per cent. The
spectral and temporal characteristics of IGR J17354-3255 are highly indicative
of a Supergiant High Mass X-ray Binary nature (SGXB). However, our inferred
dynamic ranges both at soft and hard X-rays are significantly greater than
those of classical SGXB systems, but instead are typical of intermediate
Supergiant Fast X-ray Transient (SFXTs). Finally, we note for the first time
that the observed fast flaring X-ray behaviour of IGR J17354-3255 is very
similar to that detected with AGILE from the spatially associated MeV source
AGL J1734-3310, suggesting a possible physical link between the two objects.
