In first such action in India's electoral history, the EC Wednesday ordered campaigning in nine Lok Sabha constituencies in West Bengal to end at 10 pm on Thursday night, a day before its scheduled deadline.
The decision came in the wake of Tuesday's violence between BJP and TMC workers in Kolkata.
"If a ban is intended for 72 hours, why is it starting at 10 pm tomorrow? Is it to allow the two rallies of the PM before that?" Yechury tweeted shortly after the EC's announcement.
Modi is scheduled to address rallies in Laxmikantapur and Dum Dum in West Bengal.
"The decision by the EC to stop campaigning a day in advance is not understood. The first thing being expected by EC was action against the lumpen elements of BJP and TMC for violence yesterday. Why has no action been initiated?" the CPI(M) leader asked.
The poll body invoked Article 324 of the Constitution to curtail the campaigning for the last phase of the election on May 19.
The EC also ordered the removal of West Bengal's principal secretary (home) and additional director general, CID.
Yechury alleged that his party had made several complaints and written many letters about violations and breakdown of law and order with impunity in Bengal but it had received no response from the poll body.
"On the fears of violation cited in the letter issued by the EC, where is the redressal mechanism if there is accumulation of arms or any other violation? So far there has been no action by the EC. This silence by them is widely considered as benefitting the ruling parties," he claimed.
He also tweeted a copy of a letter written to the EC by the CPI(M), demanding that the video of Tuesday's violence shot by the poll body's official videographer be released.
"If there are claims made by both sides, why has the EC not released the video recorded by the official EC videographer of the incident? That should have been the first step, before naming the culprits & punishing," Yechury said.
It was "clear" that the TMC also played a role to "provoke a confrontation in order to galvanise the atmosphere of polarisation", the CPI(M) said in the letter.
The BJP and the TMC have accused each other of inciting the violence which broke out during BJP president Amit Shah's massive road show.
During the violence, a bust of Bengali icon Ishwar Chandra Vidyasagar was also vandalised.