'Religious minority communities -- including Muslims, Christians, Buddhists, and Sikhs -- have endured ongoing violence and harassment for decades in India, and continue to live in a climate where known perpetrators commit violence with impunity,' the members of the Congress, led by Trent Franks and Betty McCollum, wrote.
'We respectfully request that during your meetings with the prime minister, the 'shared value' of the fundamental right of religious freedom will be a priority in your conversation,' they said ahead of the Ryan-Modi meeting.
'It is in the best interest of the US and India to reaffirm religious freedom as a shared value in this growing partnership and ensure that conversation concerning justice and accountability for such horrific acts of violence continues,' the letter said.
In the letter, the lawmakers cite several specific examples of violent attacks that have killed or displaced religious minorities.
Human rights groups in India have investigated and traced these attacks to specific groups, but a current climate of impunity exists in India around such attacks and many victims never receive justice, they said.
"As we consider the shared values of the US and India, due attention to the fundamental human right of religious freedom is of the utmost importance," Franks said.
"Religious minority communities in India have endured incidents of harassment, discrimination, intimidation and violent attacks for decades, often with little hope for justice. It is my sincere hope that every person in India will experience true freedom of faith, regardless of religion," he said.
"The important relationship between India and the US is based on our shared democratic values. Religious minorities in India -- Muslims, Christians, Buddhists and Sikhs -- deserve the freedom to live out their faith without fear," McCollum said.
The Congressmen who signed the letter were Chris Smith, Juan Vargas, Andre Carson, Keith Ellison, Patrick Meehan, Keith Rothfus, Randy Weber, Dan Kildee, Mike Honda, John Conyers Jr, John Garamendi, Robert Aderholt, Anna Eshoo, Joe Pitts, Barbara Lee and David Valadao.
Modi is scheduled to address a joint session of the US Congress on Wednesday.
Meanwhile, Ryan has made first of its kind arrangement for the coverage of Modi's address to the joint session of the US Congress on social media.
"Get real-time updates and video highlights from Prime Minister Modi's address by following @SpeakerRyan on Twitter," the Speakers office said, describing it as a historic address.
Congressional sources said there is a buzz on the Capitol Hill and they were expecting a large turnout from lawmakers to listen to his address.
"Throughout the day, we have been mailing offices of other Congressmen to check if they have a ticket for theaddress. Every Congressmen have been allocated one ticket. But it seems there is more demand for tickets," a Congressional aide said.
In a statement, the White House said US Vice President Joe Biden would attend Prime Minister Modi's address to a joint meeting of Congress at the United States Capitol.
Several Cabinet members of the Obama Administration and Supreme Court judges are also expected to be present among the audience.
Soon after his address Ryan will host a lunch for him.
Thereafter the Prime Minister would attend a reception hosted in his honor by jointly by the Senate and House Foreign Affairs Committees.
Congressman Ami Bera, the only Indian American lawmaker in the House of Representatives, would address the press afternoon after Modi's speech.
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