Pakistan police baton-charged and arrested political activists and lawyers, who defied a ban on demonstrations to gather to set-out on a long march to the capital, Islamabad, to force the government to reinstate the sacked judges.
As slogan chanting crowds began assembling outside the Sindh High Court, riot police attempted to break them up by baton charging and bundling lawyers into police vans, as the country's most prominent opposition leader Nawaz Sharif declared "we are ready for the long march."
Vowing to join the marchers in Lahore, Sharif accused the government of plotting to kill him, but said he won't be deterred to bring back Pakistan on the road to democracy.
"Threats to my life come from high-ranking government officials, certain topmost people in the government, my sources say," the former premier told the Guardian newspaper.
Among those arrested here were Ghafoor Ahmed, Vice President of Jamaat-e-Islami and Athar Minallah, leader of the local bar Association.
Ahead of the march, seen as a political show-down between erstwhile allies PML-N leader Nawaz Sharif and Pakistan President Asif Ali Zardari, authorities throughout the night continued their swoop rounding up scores of political leaders, right activists and lawyers in a bid to thwart the march.
The growing political confrontation is raising the spectre of a possible military intervention in the country which is prone to coups.
As international concern grows, the US special envoy Richard Holbrooke called up Pakistan Prime Minister Yousuf Raza Gilani to discuss the current unrest. The Army chief General Ashfaq Pervez Kayani had also met Gilani last night.
The government has defended its crackdown, with Information Minister Sherry Rehman saying it had been left with no other option in the face of repeated calls for "rebellion" by Nawaz Sharif and his brother, former Punjab Chief Minister Shahbaz Sharif.
Interior ministry chief Rehman Malik has asked the protesters to stay away from Islamabad and warned the Sharif brothers that their calls for a revolution amounted to sedition, a crime that can be punished with life imprisonment.
Very few senior political leaders have been detained during the crackdown though Pakistan Tehrik-e-Insaf chief Imran Khan and lawyers' leader Aitzaz Ahsan have gone into hiding following raids on their homes.
Authorities have drawn up plans to seal Rawalpindi and Islamabad for two days to prevent the protesters reaching the parliament, Dawn News channel quoted its sources as saying.
A total of 86 entry points to the two cities will be blocked with freight containers and barbed wire, the sources said.
Police have been directed not to open fire and to use non-lethal means like teargas and rubber bullets to disperse the protesters. They have also been directed to arrest all persons violating prohibitory orders.
A total of 3,700 additional police personnel from Punjab and Sindh will be deployed in the federal capital along with some 450 additional paramilitary personnel to deter the protesters, the sources said.
Meanwhile, rights group Human Rights Watch has criticised the Pakistan government's crackdown and called for it to be ended.
The group said in a statement that the detained protesters should be freed immediately and allowed to demonstrate peacefully.