The Gujarat government's competitive examination for the recruitment of junior clerks was cancelled hours before it was scheduled on Sunday after its question paper leaked, officials said.
The Gujarat Anti-Terrorist (ATS) has arrested 15 people in this connection from Vadodara, they said.
As many as 9.53 lakh candidates had applied for the exam for 1,181 posts which was to be held at 2,995 centres across the state.
Based on a tip-off, police detained a suspect and recovered a copy of the question paper of the exam early Sunday morning, after which the Gujarat Panchayat Service Selection Board (GPSSB) decided to 'postpone' the exam in the wider interest of the candidates, the board said in a statement.
State Panchayat Department's development commissioner Sandeep Kumar told reporters that the examination will be held in the next 100 days.
A Gujarat ATS officer said 15 people were arrested in this connection from Vadodara as the agency kept a close watch on the suspects in the last few days.
The state ATS took a proactive approach to ensure the exam was conducted in a fair and transparent manner, he said.
"We have arrested 15 people. They are part of a highly organised gang which operates in different states," Gujarat ATS Superintendent of Police Sunil Joshi said.
The board expressed regret for the inconvenience caused to the candidates and announced the examination will be conducted afresh at the earliest, for which the board will issue a new advertisement.
Meanwhile, candidates reached the examination centres from far off places on Sunday and expressed anger over the development.
Members of the National Students' Union of India (NSUI), the Congress's student wing, blocked roads and shouted slogans against the government even as a number of them were detained in different parts of the state, according to police.
Some of the angry candidates demanded strong action against those responsible for the paper leak.
Police teams were deployed at the exam centres and bus stands as agitated candidates expressed their anguish and anger over the development.
"Candidates feel helpless and uncertain about their future due to paper leak incidents happening regularly. The government should take care that such an incident does not recur. We travelled from far off places and took trouble to reach here only to find the exam was cancelled," said a candidate.
The Panchayat Department's development commissioner Sandeep Kumar said the postponed competitive examination will now be held in the next 100 days.
The GPSSB will announce the new exam date shortly after taking into consideration the dates of other competitive exams as well as the exam dates of schools and colleges, he said.
"It has also been decided by the board that for the next examination, candidates will be able to travel in Gujarat state transport buses free of charge based on their identity card (call letter/hall ticket) to and from the examination centres," he said.
He said in the last five years, the board has conducted various competitive examinations involving more than 30 lakh candidates to fill up to 21,000 posts.
"In these examinations, candidates have been selected in a transparent manner with all security, vigilance and care," he added.
The opposition Congress and the Aam Aadmi Party in the state demanded strict action against the culprits.
Gujarat AAP president Isudan Gadhvi demanded that the government form a Special Investigation Team (SIT) headed by a retired Supreme Court judge to investigate the paper leak cases in the state.
"Apart from the SIT, we demand that the government come up with a strict law against paper leak in the upcoming budget session of the assembly. The government should also provide a compensation of Rs 50,000 each to the candidates and make sure the candidates are not made to deposit the fees all over again," Gadhvi told reporters.
The budget session of the Gujarat assembly will be held from February 23.
Gujarat Congress spokesperson Manish Doshi claimed 15 such competitive examinations were postponed in the last 12 years due to question papers leak.
The junior clerk exam, for which the first advertisement was issued in 2016, was cancelled for the third time, he further claimed.
The Bharatiya Janata Party government had faced strong opposition from the Congress and the AAP over the issue ahead of the state Assembly elections held last month.
During the poll campaigning in the state, AAP's national convener Arvind Kejriwal had even promised to bring a strict law against exam papers leak with a provision of ten-year jail term.