It depends on the type of conductor, how many cores, type of insulation, how it is installed, etc. You will need to consider each of these factors, and check it out in the appropriate conductor data tables (e.g. in BS 761:2008).
The max current carrying capacity of
1mmsq copper is 2.2A to 2.4A
&
1mmsq Aluminium is 1.2A to 1.4A.
about 3A
Google wire circular mil.