Troops have joined police in forcefully dispersing marchers in the city of Mandalay in northern Myanmar, as protests against the military coup continued despite the deployment of extra soldiers in some areas and an eight-hour internet blackout overnight.

Images and reports from the city on Monday showed police and soldiers using rubber bullets and slingshots to disperse protesters. A student union in the city said several people had been injured.

Myanmar resurfaced online at about 9am local time on Monday after an internet-monitoring service showed a dramatic fall in connectivity from midnight. There were fears the blackout might be used as cover for mass arrests or violence.

There was no sign of that on Monday, but the country woke to extra troops on the streets of many cities including the former capital Yangon, where the new forces on the ground included the 77th light-infantry division which, during pro-democracy protests in 2007, was accused of ramming demonstrators and using live ammunition against them.

Protests continued in the city despite the show of force, albeit in numbers smaller than the peaks of Friday and the weekend. Students and Buddhist monks demonstrated in front of the troops, and a banner reading “We do not want military government” was stuck to an army vehicle outside Yangon’s central bank.