U.S. lawmakers say they are encouraged by growing defense cooperation with India but remain concerned about religious intolerance and slavery in the South Asian nation ahead of a visit by its prime minister.

Members of the Senate Foreign Relations Committee examined ties between the world's two largest democracies Tuesday in advance of Prime Minister Narendra Modi's (nah-REN'-drah MOH'-dee)'s address to Congress next month.

Committee chairman Sen. Bob Corker said it was essential that the U.S. and India stand together to uphold democratic values and norms in the Indo-Pacific region as China seeks to gain greater influence.

But he voiced concern that about half of the estimated 27 million people in slavery in the world reside in India.

Other lawmakers complained about restrictions on market access to India.