The indefinite shudown was part of a stepped up campaign by the Awami League-led alliance to force removal of controversial election officials ahead of polls in January.
Activists set fire to at least five train carriages and a bus on the outskirts of the capital Dhaka where hundreds had gathered despite an indefinite ban on rallies and demonstrations.
Vehicles were also torched or stoned in several districts in the east and north of the country.
But so far there were no reports of any casualties, police said.
The blockade follows expiry of a deadline Awami leader Sheikh Hasina had set the interim government to remove Chief Election Commissioner M A Aziz and his deputies for their alleged bias towards the Bangladesh Nationalist Party (BNP) of Begum Khaleda Zia, whose term as prime minister ended last month.
''We have instructed our followers to paralyse the country ...
including ports, buses, trains and ferries,'' Awami general secretary Abdul Jalil told reporters.
The BNP denies the allegation of bias, accusing the Awami League of trying to push the country into anarchy and sabotage the polls.
''They are working on a sinister design to halt the process of the election in January,'' BNP secretary-general Abdul Mannan Bhuiyan said.
Separately, US Assistant Secretary of State Richard Boucher wound up his trip to the country holding talks with President Iajuddin Ahmed who also leads the caretaker administration.
Boucher told reporters the Election Commission was a constitutional authority but must win the trust of the people.
''The decisions should be credible to the voters,'' he said adding that the US fully supported the election process. yesterday he urged political parties to give up the path of confrontation.
RISING TENSION Tensions have been running high in Bangladesh in the run-up to the elections.
At least 30 people were killed and hundreds injured in clashes between rival political activists in late October over the demand for electoral reforms.
Today day, authorities deployed nearly 15,000 police, elite forces and paramilitary troops to maintain law and order in the capital, home to 10 million people.
''Any efforts to break our protest will only trigger violence,'' said a protester in the capital.
Correspondents in the southern port city of Chittagong, the northeastern city of Sylhet and Khulna in the southwest said the blockade had also taken effect there and in nearby towns.
Port operations were paralysed in Chittagong and in Khulna, and schools were shut across the country today, a working day in Bangladesh.
REUTERS SP RN1355