India's Assam state has scrapped an 89-year-old law that allowed marriage involving underage Muslims, against opposition from leaders of the minority community who called the plan an attempt to polarise voters on religious lines ahead of elections.

Assam, which has the highest percentage of Muslims among Indian states at 34%, has previously said it wants to implement uniform civil laws for marriage, divorce, adoption and inheritance, as the state of Uttarakhand did earlier this month.

Nationwide, Hindus, Muslims, Christians and other groups follow their own laws and customs or a secular code for such matters. Prime Minister Narendra Modi's Bharatiya Janata Party (BJP) has promised a Uniform Civil Code, opposed by Muslims.

Assam repealed the Assam Muslim Marriages and Divorces Registration Act, 1935, effective from Feb. 24, Assam Chief Minister Himanta Biswa Sarma wrote on X on Saturday.

"This act contained provisions allowing marriage registration even if the bride and groom had not reached the legal ages of 18 and 21... This move marks another significant step towards prohibiting child marriages in Assam."

Asked by Reuters on Sunday whether the northeastern state would implement a Uniform Civil Code before general elections due by May, Sarma said: "Not immediately".

Many Muslims in Assam trace their roots to the neighbouring Bengali-speaking and Muslim-majority country of Bangladesh. Tension often flares between the Muslims and ethnic Assamese, who are mostly Hindu.

The BJP, the governing party in Assam - and Uttarakhand - calls itself the champion of ethnic communities.

Muslim opposition leaders said repealing the colonial-era law was discriminatory.

"They want to polarise their voters by provoking Muslims, which Muslims will not let happen," Badruddin Ajmal, a lawmaker from Assam who heads the All India United Democratic Front that mainly fights for Muslim causes, told reporters on Saturday.

"It's a first step towards bringing a Uniform Civil Code, but this is how the BJP government will come to an end in Assam."

(Reporting by Tora Agarwala in Guwahati; Editing by Christopher Cushing)