"Belgian involvement could only be possible if there is a clear UN mandate. For us, it is out of the question that Belgium would positively respond to such a US request at present," the Socialist Party of Wallonia said in a statement.
A US-led coalition of some 60 nations has been conducting airstrikes against Daesh targets in Iraq and Syria since 2014 without the UN Security Council's approval. Daesh has been designated as a terrorist group and is outlawed in the United States and Russia as well as in other countries.
As part of the coalition, Belgium launched its first attacks against Daesh in Iraq in late 2014, but firmly refused to become involved in a full-scale air campaign in war-torn Syria.
Belgium's contribution to the coalition comprises six F-16 multirole fighters and a contingent of 120 support staff.
