Vallipuram Parvathi, who is believed to have suffered a stroke, travelled to the southern Indian state of Tamil Nadu from Malaysia on Friday night.

She was sent back without being allowed to leave the aircraft.

Security had been stepped up around Chennai airport where a small group of supporters of the Tamil Tigers had gathered.

There's been no comment so far from the Indian government. Velupillai Prabhakaran was killed by Sri Lankan security forces in May last year.