Lucknow: Hundreds of students, worked up owing to the paper leak of the Uttar Pradesh Provincial Civil Services (PCS) exams last week, on Wednesday got violent and set ablaze a city transport bus in Allahabad, police said.

Violence broke out after hundreds of PCS aspirants gathered in front of the Public Service Commission office and began a protest.

The sit-in soon turned violent and the agitating students started pelting stones at the building, passers-by and a police contingent deployed outside the PCS office. They also set on fire a transport bus.

Police resorted to a cane charge to control the irate mob and fired rubber bullets to disperse the unruly crowd.

An official said that the situation was soon brought under control and heavy security deployment put in place to avoid any recurrence of the violence.

The question paper of the PCS test was leaked on March 29 on the messaging service WhatsApp just before the start of the examination.

Hundreds of thousands of civil service aspirants were left in the lurch following the paper leak.

While the preliminary examination is now scheduled for April 10, the students have approached the Allahabad High Court seeking cancellation of the examination.

Around 450,000 candidates appeared at 917 centres across the state, including 70,000 candidates who took the test at 148 centres in Lucknow.

The opposition parties, including the BJP, have accused top political leaders of the ruling party of being hand in glove with the people who leaked the paper.

Vijay Bahadur Pathak, state spokesman of the BJP, said that connivance of the high and mighty cannot be ruled out in the leak.

“There is lurking suspicion ... the entire thing unravelled, then the denial and attempts to cover up by the Akhilesh Yadav government,” he added.

Thousands of students appearing for the examination have taken to the streets since then and have been accusing the Akhilesh Yadav government for the leak, which could jeopardise their careers.