Making a breakthrough in its investigation into the police firing in Nandigram on March 14, the CBI on Saturday arrested 10 people and seized a large quantity of arms and ammunition from them.

East Midnapore's Superintendent of Police G A Srinivas told PTI the arrests were made at Khejuri on Saturday evening during raids by the CBI. He declined to specify the political affiliation of those arrested.

Srinivas said 14 improvised firearms, 500 rounds of assorted ammunition, binoculars and cellphones were seized by the CBI team from a brick kiln.

Earlier in the day, CBI sleuths from Delhi accompanied by local officers and forensic experts inspected several areas at Gokulnagar village near Nandigram and dug up the earth at some places to ascertain whether arms and bodies had been buried there as was claimed by local people.

Reporters were barred by police from going near the places visited by the team, and CBI officials did not respond to queries from the media.

The CBI team also went to Tamluk Hospital and questioned those who were injured in Wednesday's police action that claimed 14 lives. They enquired about the circumstances in which they were injured and who was responsible for it.

The team had on Friday visited Sonachura village and collected evidence.

The CBI began probing the police firing in Nandigram, which has witnessed protests against the acquisition of land for a SEZ, on the directive of the Calcutta high court issued in response to a PIL by several lawyers.