The Election Commission of India (ECI) has found the report submitted by the West Bengal government on the alleged attack on Chief Minister Mamata Banerjee in Nandigram on March 10 as "sketchy" and asked Chief Secretary Alapan Bandyopadhyay to elaborate it, a poll official said on Saturday.

The chief secretary has been asked to furnish details like how the incident took place and who could be behind it by Saturday, he said.

"The report submitted by the West Bengal government appeared to be quite sketchy and without any details of the incident like how it happened or who could be behind it. We have asked the state administration to furnish more details," the official told PTI.

The state government's report submitted to the ECI on Friday evening referred to the presence of a huge crowd at the spot but has no mention of the "4-5 people", who Banerjee alleged had attacked her, he said.

It said there was no clear video footage of the alleged attack that took place in Birulia Bazar of Nandigram in Purba Medinipur district on Wednesday evening.

After the incident, the ECI sought a report from the state government and appointed two poll observers for the state.

The chief minister has left her Bhawanipur constituency in Calcutta to fight former aide and BJP candidate Suvendu Adhikari in Nandigram, where an anti-land acquisition movement catapulted her party to power in 2011.

Elections to the 294-member assembly will be held from March 27 to April 29. Results will be declared on May 2.