The deadliest clashes so far broke out Tuesday between Syrian government forces and Kurdish fighters in a contested area of the northern city of Aleppo, as efforts to merge the U.S.-backed Syrian Democratic Forces with the national army have shown little progress.

Syria 's state-run SANA news agency said a soldier was killed and three others were wounded in an attack by the SDF. State TV later reported that three civilians, including two women, were killed and others were wounded, including two children, in shelling of a residential area that it blamed on the SDF. SANA also said nine Aleppo Directorate of Agriculture employees were wounded by SDF shelling that hit its office.