Local reports said fighting also was taking place in the center of the town.
By the end of 2016, the two, who back opposite sides in the Syrian war, were co-operating to reach a ceasefire in Aleppo.
"The al-Bab operation must be completed immediately in the period ahead".
On Thursday, government troops seized a village south of al-Bab, bringing them less than 3 kilometers (1.5 miles) from the town, according to opposition monitors.
Following Thursday's incident, the Russian defence ministry said chief of the general staff Valery Gerasimov and his Turkish counterpart, Hulusi Akar, had spoken on the phone and "agreed on closer coordination of joint actions".
IS fighters "are putting up a tough fight in and around al-Bab", said Ahed al-Hendi, a Syrian affairs analyst in Washington.
Turkish media say 10 Turkish soldiers have been killed in the fighting in recent days.
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Video here shows fighters from the Hamza Brigade at several locations identifiable as being on the western outskirts of al-Bab.
Located in northeastern Syria, Raqqa province is the de facto capital of the so-called Islamic State (ISIS).
A map showing who controls areas of north-western Syria. It seems that just as in Al-Bab ISIS is now intent on defending territory, so in Deir Ezzor it is now intent on capturing territory, in both cases regardless of cost.
Free Syrian Army soldiers look poised to enter al-Bab after rebel forces captured hills surrounding the town while regime troops are leading a separate assault from the south.
FILE - People ride in a vehicle stacked with their belongings after fleeing clashes in the northern Syrian town of al-Bab, Syria, Jan. 26, 2017. The U.S. -led coalition and its local partners are advancing toward Raqqa and gradually besieging the area.
"Information was obtained indicating that some group members were going to carry out sensational attacks in our country in line with orders from senior members in Syria", the Gaziantep governor's office said in a written statement.