  The aim of this work is to investigate and characterise non-thermal particle
behaviour in a three-dimensional (3D) magnetohydrodynamical (MHD) model of
unstable multi-threaded flaring coronal loops. We have used a numerical scheme
which solves the relativistic guiding centre approximation to study the motion
of electrons and protons. The scheme uses snapshots from high resolution
numerical MHD simulations of coronal loops containing two threads, where a
single thread becomes unstable and (in one case) destabilises and merges with
an additional thread. The particle responses to the reconnection and
fragmentation in MHD simulations of two loop threads are examined in detail. We
illustrate the role played by uniform background resistivity and distinguish
this from the role of anomalous resistivity using orbits in an MHD simulation
where only one thread becomes unstable without destabilising further loop
threads. We examine the (scalable) orbit energy gains and final positions
recovered at different stages of a second MHD simulation wherein a secondary
loop thread is destabilised by (and merges with) the first thread. We compare
these results with other theoretical particle acceleration models in the
context of observed energetic particle populations during solar flares.
