Telecoms links were widely disrupted in Bangladesh on Friday, with television news channels going off the air amid violent student protests against quotas for government jobs that have killed nearly two dozen people this week.

Sparked by student anger against the controversial quotas, the protests, some analysts say, are also being fuelled by economic woes, such as high inflation, growing unemployment and shrinking reserves of foreign exchange.

The government offered no immediate comment on Friday's severed communications, but said police in Dhaka, the capital, had barred all public meetings and processions indefinitely.

Police fired tear gas to scatter protesters in some zones of fresh violence, Reuters journalists said, adding that security forces and protesters milled about in the streets of Dhaka.

Protesters blocked roads at many places and threw bricks at security forces, the English-language website of the Bengali newspaper Prothom Alo said.

Thursday's violence in 47 of Bangladesh's 64 districts killed 27 and injured 1,500, it added, while French news agency AFP put the day's toll at 32, citing a police spokesman as saying 100 policemen were injured with 50 police booths burnt.

Reuters, which reported 13 dead, up from a tally of six earlier in the week, could not immediately verify the higher figures.

Citing unidentified sources, India's Economic Times newspaper said Prime Minister Sheikh Hasina's government was forced to call in the army late on Thursday to help maintain order.

Reuters could not independently verify the details.

The protests have also opened old and sensitive political faultlines between those who fought for Bangladesh's independence from Pakistan in 1971 and those accused of collaborating with Islamabad.

The former include the Awami League ruling party of Hasina, who branded the protesters "razakar", making use of a term that described independence-era collaborators.

Authorities had cut some mobile services on Thursday to try to quell the unrest, but the disruption widened nationwide the next morning, Reuters witnesses said.

Overseas telephone calls and those through the internet were crippled, while the websites of several Bangladesh newspapers did not update on Friday and were also inactive on social media.

A few voice calls went through, but there ws no mobile data or broadband, a Reuters photographer in Dhaka said, adding that even text messages were not being transmitted.

News television channels and state broadcaster BTV went off the air, although entertainment channels were normal, a Reuters witness said.

Some news channels displayed a message blaming technical issues, and promising to resume programming soon, the witness said.

Streets in Dhaka were deserted with little traffic on Friday, a weekly holiday in the Muslim-majority nation, but the witness added that a protest rally had been called for 0800 GMT at the main mosque.

There were no flight disruptions at the main international airport, aviation website Flightradar24 showed.