Chief minister Mamata Banerjee walked in and stayed put at a polling booth in Nandigram on Thursday afternoon amid complaints of rigging and booth capturing during the second phase of voting in Bengal.

Contesting from Nandigram, Mamata stayed indoors at her rented house in Reyapara, when she received information about trouble brewing at Boyal Maqtab primary school booth number 7, a known trouble-spot in the constituency.

Around 1.10pm, Mamata's convoy left for the Boyal school. She was there for over 39 minutes till reports last came in. Voting started in the booth at 7.00am and is supposed to continue till 6.30pm.

Mamata barged into the polling booth and asked the presiding officer why there were so many complaints. She also spoke with the booth agents and others, who alleged that the BJP had captured the booth since morning and were not allowing anyone to vote.

From the booth, Mamata spoke with Governor Jagdeep Dhankar and wrote a two-page letter to the Election Commission of India.

"I am the candidate here, so this letter has to be treated as an FIR," Mamata was heard saying.

While the chief minister was inside, there were clashes between rival camps. More police personnel were rushed to the school to prevent an escalation in violence.

The chief minister's presence seemed to encourage the Trimamul supporters to get aggressive.

"I am afraid of the safety and security of the local people once polling is over. There are many outsiders who are in the area and they pose a threat to the locals. I cannot leave now," Mamata said.

Two observers from the Election Commission met Mamata at the booth and tried to pacify her, but she wouldn't budge. EC special observer Nagenra Tripathi also arrived at the spot and gave a patient hearing to Mamata.

Earlier in the morning, Trinamul sources had said Mamata would leave for North Bengal on Friday morning instead of Thursday evening.

Throughout the day there were reports of clashes and intimidation in different parts of Nandigram.

A Trinamul polling agent refused to return to the booth after being forced to leave facing intimidation. When the police personnel went to bring him back, his family members said the forces from the central agencies could not protect him forever.

In neighbouring Chandipur, a BJP worker Gour Pradhan was critically injured after being allegedly attacked by one Nantu Pradhan.