Police in India have arrested a man in connection with a series of explosions at a Jehovah's Witnesses meeting in the southern state of Kerala.

Three people were killed and more than 50 injured in the blasts at a programme held by the Christian-based religious movement on Sunday.

Police said the man, Dominic Martin, was arrested under an anti-terror law.

He had earlier posted a video claiming responsibility for the attacks and surrendered to police.

The blasts took place during the last day of a prayer session organised by Jehovah's Witnesses in the town of Kalamassery, about 10km (six miles) north-east of the port city of Kochi (Cochin). More than 2,000 people were attending the three-day event.

TA Sreekumar, a regional spokesperson for the Jehovah's Witnesses, told local media that the first blast took place in the middle of a hall, and two more explosions took place seconds later on either sides of the hall.

Two women who attended the meeting died on Sunday, while a 12-year-old girl with 95% burns succumbed to her injuries on Monday.

Hours after the explosions, Mr Martin posted a video on Facebook claiming to be a former member of the Jehovah's Witnesses who planned the blasts because he was angry with the group's teachings. But Mr Sreekumer told Reuters that Mr Martin was "not a registered member".

Police said Mr Martin was from Kerala state and had previously worked in Dubai.

"We are convinced that he committed the crime based on his confession and corroborating pieces of evidence we collected," Kochi city police commissioner A Akbar said on Monday.

Mr Akbar said Mr Martin was co-operating with the police.

The blasts sent shockwaves across the country, and security was stepped up in Delhi, Mumbai and other cities.

The Jehovah's Witnesses is a religious movement which believes that traditional Christian churches have deviated from the actual teachings of the Bible and Armageddon is imminent.

The group, which claims to have about 8.7 million followers worldwide and some 60,000 in India, has a strong presence in Kerala and is known for door-to-door evangelism in the state.

Queen Richard, a member of Jehovah's Witnesses who was in the hall when the bomb exploded, said she initially thought a short circuit had caused the explosion.

"As we closed our eyes and prayed, we heard that explosion in the centre of the hall. There was a huge flame," she said, adding that she and her husband, who has a disability, found it difficult to leave the hall.

"As soon as I got outside I fainted and fell down," she said.