When Mahatma Gandhi was cremated, legend has it that his estranged eldest son, Harilal, a Muslim convert, alcoholic and vagrant, either boycotted the ceremony or arrived too late to perform his filial duties.

In the outpouring of grief that followed, Gandhi's ashes were poured into dozens of small steel urns that were distributed around India, denying him the proper Hindu burial that he had requested.

Sixty years after Gandhi's murder, Harilal's granddaughter is to scatter some of his recently discovered ashes in the Arabian Sea in a ritual designed to lay the Mahatma to rest — and heal the rift with his long-dead son.

Gandhi's descendants have agreed to perform the ceremony off the coast of Bombay on January 30, the 60th anniversary of his assassination by a Hindu extremist in Delhi.

“What should have been done then will be done now,” Tushar Gandhi, one of the Mahatma's great-grandsons, told The Times. “We all felt that this was the right thing. If Harilal had been there and he himself had done it, then that reconciliation might have happened.”

Hindu custom dictates that the oldest son should scatter his father's ashes into a river or the sea within 13 days. But relations between Gandhi and Harilal were so bad that they had not spoken in years and no one in the family even knew where the son was.

As a child, Harilal was devoted to his father and wanted to become a barrister, like him, but rebelled against everything he stood for after Gandhi refused to support his studies at the Bar in London. Harilal became an alcoholic, a gambler and a trader in imported British clothes, even as his father launched a nationwide boycott of British goods. He converted to Islam and changed his name to Abdullah before his own death in a Bombay hospital later in 1948.

“It was a lack of communication and understanding that compounded the tragedy of two strong-willed people,” Tushar said. “It was incredibly sad that they couldn't come to terms with each other.”

The urns of Gandhi's ashes were distributed around India to be immersed in rivers in multiple funerals, but many remained in the hands of devotees, including one that is still enshrined in an ashram in California.

In 1997 Tushar immersed one urn at the holy spot where the Ganges and Yamuna rivers meet. He had found it in a bank vault in India and won a Supreme Court battle for its custody.

He said that another urn had been sent to the Mani Bhavan Gandhi museum in Bombay last year by an Indian businessman in Dubai whose father had been a close friend of the Mahatma. The museum had planned to put the ashes on display, but when Tushar heard about it he asked if they could be immersed instead.

Gopal Krishna Gandhi, another great-grandson of the Mahatma, who is the governor of the state of West Bengal, then suggested that they invite Harilal's grandchildren to perform the ritual.

Nilamben Parikh, Harilal's granddaughter, who lives in Gujarat, is expected to lead the ceremony - the first time that one of her side of the family has attended a commemoration of Gandhi's death. “She was very moved that she could get a chance to perform something like this on behalf of her grandfather,” Tushar said.

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