DHAKA (AFP) - Bangladeshi telecoms authorities Sunday shut down smartphone messaging and voice services Viber and Tango, which have become a popular communication medium for supporters of the anti-government protests now in their third week.

The Bangladesh Telecommunications and Regulatory Commission closed down the apps "for the time being" on orders from law enforcement and security agencies, a commission spokesman told AFP.

He did not give reasons for the decision, but local television station Channel 24 said Viber and Tango were shut down to prevent protesters from "exchanging information" across the country.

Viber and Tango have been popular among opposition protesters, including activists from the Bangladesh Nationalist Party (BNP) and its Islamist allies who have launched a crippling nationwide transport blockade to try to topple the government.

The protests, now in their third week, have turned increasingly violent with activists firebombing hundreds of buses and trucks and security forces retaliating with live bullets or tear gas.

At least 25 people have died in the latest violence including about a dozen burnt to death after protesters firebombed buses.

The government has deployed thousands of police, paramilitaries and an elite anti-militant force to crack down on the protesters. But the violence has continued unabated, disrupting transport services and shipments of garments, the country's biggest export.