Thiruvananthapuram, Mar 25 (IANS): A day after veteran anthropologist and sociologist Filippo Osella was not allowed entry to India after he reached Kerala and sent back to the UK, the state's ruling CPI-M on Friday demanded the Centre explain the reason for this step.

Raising the issue was CPI-M state Secretary and Politburo member Kodiyeri Balakrishnan who slammed the Centre for doing this.

"It has now come to be known that the Centre directed the immigration officials to send him back. It's most unfortunate that the professor was not given the reason on why he was being sent back and this does not augur well... this is not the way it should have been done as he had a valid visa," he said.

As Osella landed at Thiruvanthapuram on Thursday morning, he was received by an official who took him to the immigration desk and after a brief while, he was told that he was being deported.

Airport officials were tight-lipped on the reason for the deportation, only saying that they were doing their duty.

A Professor of Anthropology and South Asian Studies at the University of Sussex, the 65-year-old Osella is an expert on Kerala and had come to take part in a seminar scheduled for Friday.

Incidentally, Osella has a valid research visa till April and his return was slated much before the expiry.