Bangladesh Prime Minister Sheikh Hasina urged students to go home on Sunday as police fired tear gas at teenage protesters during an eighth day of unprecedented demonstrations over road safety which have paralysed parts of Dhaka.

Students in their tens of thousands have brought parts of the capital to a standstill since two teenagers were killed by a speeding bus.

The unrest quickly spread beyond the capital. Authorities have shut down mobile internet services across swathes of the country, officials and local media said.

On Saturday the protests took a violent turn in Dhaka's Jigatala neighbourhood, with more than 100 people injured as police fired rubber bullets at demonstrators.

A car carrying US ambassador Marcia Bernicat was also attacked by "armed men" but she escaped unscathed, the embassy said.