Iraq closed its border with Syria on Sunday to stop what it calls foreign fighters entering the country, as a U.S.-backed military operation to wipe out suspected terrorists in the city of Tal Afar continued. Prime Minister Ibrahim Jaafari said on Sunday he was also imposing an overnight curfew in the north western region of Rabiah, on the main road from the Syrian border to the northern city of Mosul, near Tal Afar. Thousands of Iraqi troops backed by U.S. forces launched an attack on rebels in Tal Afar starting at 2.00 a.m. on Saturday (2200 GMT on Friday). Defense Minister Saadoun Dulaimi said that after the assault, government forces were ready to strike insurgents in four other northwestern towns, Reuters reported.