MUMBAI (AFP) - Ashes of India's freedom icon Mahatma Gandhi were scattered on Wednesday off the coast of Mumbai in a ceremony marking the 60th anniversary of his assassination by a Hindu fanatic.

A copper urn containing some of the ashes was opened and the ashes mixed with water and poured into the Arabian Sea by his great-granddaughter Nilamben Parikh in accordance with Hindu rites.

"This is a day for deep thought. This day will help us think how to move forward," Parikh, 75, told reporters.

Mohandas Karamchand Gandhi -- called Mahatma or "Great Soul" -- spearheaded a non-violent campaign against the British Raj which finally saw India gain its independence in 1947.

Even as India's economy booms, creating new wealth, Gandhi is still regarded as the nation's moral conscience and a rebuke to crass materialism and corruption.

Parikh, along with 10 other family members boarded a boat and travelled about a kilometre (nearly a mile) out to sea to perform the ritual.

The ashes had turned up last year when an urn was sent by Indian businessman Bharat Narayan to Mumbai's Mani Bhavan museum, where Gandhi had lived while visiting the city and was the focal point of his political activities.

Hindus cremate their dead and the ashes normally are supposed to be scattered in rivers or the sea after 13 days.

But so great was the mourning after Gandhi was shot dead on January 30, 1948 en route to a New Delhi prayer meeting by a Hindu fanatic angered by the leader's goodwillpolicy towards Muslims that his ashes were divided into various urns and sent to towns and villages across India for memorial services.

One urn ended up with the businessman's deceased parents who preserved them.

Before the ashes were scattered, Gandhi's family sang his favourite hymns as a police band played. Home Minister Shivraj Patil also attended the ceremony.

Gandhi's great-granddaughter Parikh recollected childhood memories of him, saying, "He would pat me hard on my back with fondness."

Parikh is descended from Gandhi's eldest son, Harilal, who had a tortured relationship with his famous parent and was not at his funeral, breaking with Hindu tradition by which the eldest son lights his father's funeral pyre.

Parikh's participation in the ceremony was a gesture of reconciliation, family members said.

"Harilal Gandhi could never really fulfil his obligation," Gandhi's great-grandson Tushar Gandhi told AFP. "It's symbolic for the family that Harilal's granddaughter immersed the ashes. Nilamben did (in some ways) what Harilal should have done."

The origin of the rift between Gandhi and Harilal has been a topic of huge interest for scholars. Harilal, who died a lonely death in hospital five months after his father, converted to Islam, reconverted to Hinduism and ended up an alcoholic.

Some scholars say the trouble began when Harilal wanted to become a barrister like his father. His father had an offer to finance a follower's legal education in London but chose another student, saying he could not favour his family.

Many say Gandhi's single-mindedness and asceticism served him well as a political leader but made him unfeeling as a father.

Tushar Gandhi said "the rift between father and son has not extended to the existing families -- we are all close now."

Meanwhile, Prime Minister Manmohan Singh attended an inter-religious prayer meeting at the memorial marking Gandhi's cremation site at Rajghat in New Delhi.

In 1997, another urn containing Gandhi's ashes was found in a bank locker and they were later scattered.

"This is an emotional time for the family and I hope there are no more ashes found," said Tushar Gandhi.