Contingents of police were deployed at the Hyderabad-Karachi toll plaza, Jamshoro and Kotri.
Police officials did not mince words in telling the lawyers that they had been directed not to allow them to proceed to Karachi.
Railways authorities stopped the Shahbaz Express, the Shahnawaz Express and the Bolan Express at the Kotri railway station on the pretext of security reasons.
Hyderabad District Bar Association general-secretary Noorul Haque Qureshi said the SHO of the GOR police station, Hassan Abidi, took away their bus and parked it at the A-section police station.
Jamshoro DPO Khamiso Khan Memon stopped a large number of lawyers travelling in 20 vehicles and activists of the Jamaat-i-Islami on the Super Highway.
The DPO said that he had received directives not to allow them to leave for Karachi.
Around 50 lawyers from Tando Allahyar were prevented at the by-pass.
Police deployed on the Thatta-Karachi route forced a large number of lawyers and activists of opposition parties to return.