US President Donald Trump and Indian Prime Minister Narendra Modi have vowed a close, personal friendship at a rare mass rally full of of tens of thousands of Indian-Americans.

The two leaders, like-minded nationalists fond of fiery rallies and sceptical of traditional media, heaped praise on each other in a football stadium in Houston.

To the bhangra beats of four drummers in saffron turbans, Trump and Modi made a grand entrance to the “Howdy, Modi!” event with arms clenched together to ecstatic cheers from a crowd estimated by organisers at 50,000.

Trump won his biggest applause when he told the gathering – many wearing the saffron of Modi’s right-wing Bharatiya Janata Party – “We are committed to protecting innocent civilians from the threat of radical Islamic terrorism.”

Taking the flavour of one of the President’s own boisterous rallies, Modi later asked the crowd to give a standing ovation to Trump for his stance.

Trump has stood by the Indian leader during controversial decisions this year, including his revocation of autonomy for Muslim-majority Kashmir and his order for jets to enter Pakistani territory in response to a suicide bombing.

With Trump watching in the front row and listening to the translation, Modi made a clear reference to rival Pakistan, which controls part of Kashmir and has sought to rally international attention over the Himalayan territory.

Modi said he was seeking equal status and development for Kashmir, adding that his actions were “causing discomfort to some people unable to manage their own country” and who “nurture terrorism”.

India has also faced strong criticism from human rights experts for shutting down virtually all internet and cellular communications across much of Kashmir.

Protesters gathered outside of the NRG Stadium with placards and shirts reading, “Free Kashmir” and accused Modi of violating religious freedom – a cause frequently evoked by the Trump administration. (AFP)