There have been calls for India to do more to protect the religious freedom of minority faiths after reports that hundreds of Christians have been arrested under controversial anti-conversion laws.

UCA News reports that 398 Christians - mostly Protestant pastors and church members - have been arrested in the state of Uttar Pradesh since the law was passed there three years ago.

There have been reports of further arrests in the Indian press, with 42 Christians, including 27 pastors, brought in for questioning in Uttar Pradesh at the end of last month.

They were rounded up after a complaint was lodged that they had been trying to convert tribal and poor people by fraudulent means. According to reports, police confiscated their religious books and laptops and two in the group were formally arrested.

Release International, a ministry that supports persecuted Christians worldwide, is calling on the Indian government to overturn the "draconian" anti-conversion laws, which exist in 12 out of India's 28 states.

It said that while the laws are intended to prevent conversion by force, in reality they are preventing Christians from sharing their faith at all, despite this being permitted by the Indian Constitution.

Release International CEO Paul Robinson said that the laws have led to pastors being arrested under false allegations and reports of women and children being terrorised as they return home from church meetings.

"In the worst cases, pastors have been beaten up and a few have been killed," he said.

The warning comes after months of violence and bloodshed targeting Christians in the north-eastern state of Manipur and ahead of important national elections next year, which Release fears will lead to further gains for the Hindu nationalist BJP party.

"Given the prevailing trend, the persecution of Christians in India is likely to increase," said Mr Robinson.

"Year upon year, our partners are reporting a rise in the persecution of Christians in India."

He called for the anti-conversion laws to be repealed to prevent further bloodshed.

"We are witnessing the world's largest democracy becoming an increasingly intolerant society," he said.

"Release International calls on the Indian government to act swiftly to prevent the spread of this culture of hostility towards minority faiths, and to overturn the anti-conversion laws."