The state secondary education board barred six students from writing Madhyamik on Tuesday.

Among the six, three students of a school in North Dinajpur allegedly entered the exam hall with mobile phones, took photographs of the second language question paper and sent them to their private tutors through WhatsApp.

They received the answers through WhatsApp from their tutors, said board officials.

They were caught by invigilators around 30 minutes before the exam ended.

On Monday, the board had disallowed three other students. Two of them carried phones to the exam venues and the third tried to write the exam on her sister’s behalf, officials said.

On Tuesday, three students in Goalpokhar, North Dinajpur, allegedly entered the exam halls with phones disregarding the board’s instructions against carrying phones, smartwatches, Bluetooth and other electronic devices to exam venues.

“They took pictures of the question paper and sent them to their tutors through WhatsApp and received answers. Our invigilators caught them. They have been barred from writing the remaining papers,” said a board official.

Sources in the board said they suspect a local coaching centre was behind the act.

The matter has been reported to the police.

Another student entered the same exam venue with a phone and was caught.

“Two other students were caught with phones in exam halls in North 24-Parganas and West Burdwan. They have been barred from writing the remaining papers,” said an official.

Calls and text messages to Ramanuj Ganguly, the board president, failed to elicit any response.