An Indian couple who “married” when aged just one and three have had their wedding annulled in a ground-breaking case that activists hope will challenge the culture of child marriages.

Laxmi Sargara, 18, unknowingly wed her husband Rakesh, 20, in the desert state of Rajasthan 17 years ago after their families decided that when they grew up they would live together and have children.

In the first procedure of its type, the pair had their union legally revoked in the city of Jodhpur on Tuesday as part of a campaign against enforced child marriages.

“I was unhappy about the marriage. I told my parents who did not agree with me, then I sought help,” Sargara told AFP. “Now I am mentally relaxed and my family members are also with me.”

Child marriage is illegal in India but remains common in poor, rural communities in which it is seen as improving the financial security of both families.

The girl often remains in her parents' home until she reaches puberty and is then taken amid great celebrations to her husband's family.

But when she discovered that she was married, Sargara went for advice to social worker Kriti Bharti, who runs the Sarathi Trust in Jodhpur, a welfare organisation that lobbies for children's rights.

Bharti negotiated with Rakesh, the groom, who only uses one name, and both families to persuade them that the marriage was unfair.

“Laxmi was married to Rakesh when she was as young as one year old. Now she is 18 and a few days back she was informed by her parents that she was married and she would have to go to her husband's house,” Bharti told AFP on Wednesday.

“Hearing this, she got depressed. She did not like the boy and was not ready to go ahead with her parents' decision so she decided to refuse this marriage.

“It is the first example we know of a couple wed in childhood wanting the marriage to be annulled, and we hope that others take inspiration from it,” Bharti added.

Rakesh, who works driving an earth-mover, at first wanted to press ahead with the relationship but was convinced by his wife's fierce opposition to agree that the marriage should be revoked.

The marriage was annulled through a joint legal document signed by the two parties and validated by a public official in Jodhpur.

“To ensure that the girl does not face any problem in future, we decided to go for a legal agreement,” said Indu Chaupra, local director of the ministry of women and child development.

“The entire process was done in my supervision and my office has copies of the agreement.”

The annulment took place on the same day as the Akshaya Tritiya festival, a traditional date for mass child weddings.

On Sunday, villagers in Rajasthan attacked and injured at least 12 government officials who tried to stop a wedding of about 40 child couples. (AFP)