U.K. Prime Minister Theresa May clashed with her Indian counterpart Narendra Modi on Monday as a row over migration threatened to overshadow her attempt to set up a trade deal with India. Modi called on Britain to support more Indian students who want to enroll at universities in the U.K, as he appeared alongside May at a technology summit in New Delhi. “Education is vital for our students and will define our engagement in a shared future,” Modi said. “We must therefore encourage greater mobility and participation of young people in education and research opportunities.” Modi’s comments—as May sat beside him on stage—are likely to escalate the long-running disagreement between India and the U.K. over restrictions on student visas. May’s policy of requiring students to return home after their courses end, which dates back to her time as U.K. Home Secretary, caused the number of Indian students enrolling in British universities to fall by 50 percent. ‘Brightest and best’ Modi’s remarks were a direct response to May, who told reporters traveling with her to India that her migration rules were working well. “We have a visa system for countries outside the European Union which ensures that the brightest and the best are able to come to the United Kingdom,” the U.K. premier said. “The figures show that we issued more work visas to India than I think the U.S., Australia, Canada and China put together.” The row over migration could be a sign of the difficulties ahead for May as she seeks to pave the way for deals with countries outside the EU after leaving the bloc. She sees controlling Britain’s borders as key to satisfying the 17 million voters who backed Brexit in the June referendum, but risks antagonizing countries she will need as trade and investment partners. In her speech to the business summit on Monday, May said the U.K. and India did not need to wait for Brexit before stepping up trade between the two countries. Failure to embrace free trade will lead to stagnation, she said. “As Britain leaves the EU, we’re determined not to turn our backs on the world but to forge a new, global, outward-looking role for ourselves,” May told the conference. “We know from history what happens when countries do not embrace the opportunities of the world. They stagnate. They get poorer. They don’t protect their people; they make them worse off.” May’s trip offers a chance to recover momentum after a double-setback at home last week, when she lost a court case over Parliament’s role in Britain’s divorce from the EU and one of her lawmakers quit in protest at her strategy. Brexit Secretary David Davis is likely to lead her counter-offensive in the House of Commons on Monday as officials prepare an appeal to the Supreme Court, due to be heard next month. Newspaper Anger The ruling that May must consult Parliament before starting Brexit negotiations threatens to slow down and complicate the process of leaving the EU and could dilute her plans to deliver on the referendum result. The Daily Mail was among newspapers that criticized the judges, branding them “enemies of the people,” and sparking anger from lawyers who were further incensed by the government’s reluctance to condemn the coverage. “I believe in and value the independence of our judiciary,” May told reporters on her plane, before risking further anger by defending the newspapers. “I also value the freedom of our press. I think these both underpin our democracy.” The government has a “strong” legal case for why British lawmakers should not get to vote on when to invoke Article 50 of the Lisbon Treaty, which would begin Britain’s formal exit from the EU, she said. “We have had two court cases in the U.K. - they have come out with different decisions. The Northern Irish court found in favor of the government, the High Court found against the government,” May said. “We think we have strong legal arguments and we will be taking those arguments to the Supreme Court.” Bespoke Visas The prime minister outlined what her officials called a “bespoke” visa service for “high net-worth” Indian business leaders, and promised faster border checks for all executives traveling from India to Britain. “We want to attract more Indian businesses to the U.K., which is why it’s right to offer Indian business executives a world-class visa service tailored to their needs,” May said in a statement to journalists traveling with her. Migration is not the only point of tension between London and New Delhi. May also promised to raise the case of six former British troops who were convicted of gun running to terrorists and are in prison in India. She is under pressure from the veterans’ families and the press to secure their release. May said she has also been unable to arrange a meeting with senior figures at Tata Group, amid uncertainty for 4,000 workers at the company’s plant in Port Talbot, south Wales. The Indian multinational declared its plan to sell all or part of its British business in March, another source of strife for May’s administration.