  Current models of stellar evolution predict that stars more massive than
$\sim6\:$M$_{\odot}$ should have completely depleted all lithium (Li) in their
atmospheres by the time when they reach the He core burning phase. Against
this, a non-negligible number of red giants with masses $>6\:$M$_{\odot}$
presenting strong Li lines have recently been reported. Motivated by this
finding, we have carried out a spectroscopic survey of red supergiants (RSGs)
in the Perseus Arm and a selection of young open clusters in the Magellanic
Clouds to assess the presence of the Li I $\lambda$6708 doublet line. Based on
a sample of >70 objects, close to one third of RSGs in the Perseus Arm display
noticeable Li lines, with perhaps a trend towards a lower fraction among more
luminous stars. The samples in the Magellanic Clouds are not as large, but hint
at a metallicity dependence. Twenty one RSGs in 5 LMC clusters show a very high
fraction of Li detection, around 40%. Conversely, 17 RSGs in 5 SMC clusters
give only one secure detection. The interpretation of these observational
results is not straightforward, but a mechanism for Li production seems most
likely. Further characterisation work is ongoing, while theoretical studies
into this matter are urgently needed.
