Explosive personal letters in which Mahatma Gandhi accuses his son of incest rape are to be auctioned in the UK next week, according to the Press Trust of India.

Mullock's Auctioneers are due to auction off three letters, in which Gandhi, a symbol of peace and one of the most iconic figures of the 20th century, accuses his son Harilal of raping his own daughter, Manu.

The letters are expected to fetch Mullock's between £50,000 and £60,000.

In one of the letters, Gandhi writes to Harilal that "you should know that your problem has become much more difficult for me even more than our national freedom. Manu is telling me a number of dangerous things about you."

The letter, written in June 1935 after Manu had visited her grandfather in Ahmedabad, continues: "She says that you had raped her even before she was eight years and she was so badly hurt that medical treatment also had to be taken."

Another letter, also autographed by Gandhi, urges his son to "please let me have the pure truth, please tell me if you are still interested in alcohol and debauchery. I wish that you would rather die than resort to alcohol in any manner."

Harilal had renounced ties with his father in 1911, after Gandhi refused to provide him a western education saying that it would not help in the freedom struggle against the British Raj.

"The letters are written in Gujarati and are in good condition. These have come via descent from a branch of Gandhi's family to the present vendor" Mullock's said.

"As far as we are aware they have never before been seen in public and as such they provide remarkable new information on the troubled relationship Gandhi had with his son."

Mullock's noted that the letters were "in remarkably good condition in spite of the fact that Gandhi tended to use the cheapest paper and materials for his correspondence".

"We believe that these letters have never before been seen publicly and therefore they provide a highly important primary source of information on Gandhi and the struggle for Indian independence."

Mullock's previously auctioned a package of 50 rare personal belongings of Gandhi, including his blood and will, for £287,000.

Gandhi's will to his son got the highest bid of £50,000, trailed closely by a shawl made by him, which went for £40,000. His blood commanded £7,000, eating bowl £12,000, and drinking vessel £8,000.