Dhaka remained virtually cut off from the rest of the Bangladesh as hundreds of thousands of Islamists besieged the capital city to press home their 13-point demands which mainly include enactment of an anti-blasphemy law.

Long-distance buses plying between Dhaka and outlying Bangladesh places stayed off the roads from Sunday morning as the Islamists took position in six main entry points of Dhaka.

Leaders of Hefajat-e-Islam, a group of non-political Islamic scholars who draw support from thousands of people across Bangladesh, had earlier expressed the hope that nearly half a million people would join their activists of Dhaka to make the siege program a success.

Bangladeshi Prime Minister Sheikh Hasina urged Hefajat to call off the program from a press briefing on Friday evening while she gave assurance of meeting many of its 13-point demands.

But Hasina had earlier rejected Hefajat's demand for enacting an anti-blasphemy law stipulating punishment for defaming Islam and Prophet Muhammad.

Hefajat leaders say they are all set to call off the program at 2:00 p.m. (local time) through holding a rally in front of Dhaka's Baitul Mukarram mosque. But its appeal for permission to hold the rally was turned down Saturday.

Hefajat threatened to go tough if the government tries to create obstacles to its peaceful program.

The group has called the program apparently to gear up its ongoing campaign against the Shahbagh movement demanding capital punishment for war criminals and a ban on Bangladesh Jamaat-e- Islami party, many top leaders of which allegedly committed crimes against humanity during the country's nine-month liberation war in 1971.

Although the bloggers, some of whom reportedly spearheaded Bangladesh's Shahbag Square movement, have already denied the blasphemy allegations brought against them, the group, allegedly backed by Bangladesh-Jamaat-e-Islami party, has continued their movement, raising fears of a new round of violence.

The group said it demands restoration of the phrase "absolute faith and trust in the Almighty Allah" in the constitution, enactment of an anti-blasphemy law and punishment of "atheist bloggers".

Hefajat-e-Islam earlier on April 6 held a long march demanding punishment for the "atheist bloggers", several of whom have already been arrested.

Political tension in Bangladesh heightened in the recent months as the 18-party opposition alliance, which have already dismissed the tribunal as a government "show trial", geared up anti- government agitation programs, demanding restoration of a non- party caretaker government system to hold parliamentary elections slated for early 2014.

Former Prime Minister Khaleda Zia from the rally slapped an ultimatum on the government to meet the opposition's demand for restoration of the caretaker government system within 48 hours.

Nearly 100 people, including several policemen and dozens of Jamaat leaders and activists, were killed and hundreds of others injured in the riots erupted since a tribunal awarded death sentence to the Jamaat's Vice President Delwar Hosssain Sayeede for war crimes in 1971 on Feb. 28.