The United States is committed to deepening its relationship with India, Secretary of State Rex Tillerson said ahead of his first official visit to New Delhi next week.

In a speech at the Centre for Strategic and International Studies in Washington, he said the US was prepared to ensure India had even greater defence capabilities.

"Secretary Mattis has said that the world's two greatest democracies should have the two greatest militaries. I couldn't agree more," Mr Tillerson said, referring to US Defence Secretary James Mattis.

"The Trump Administration is determined to dramatically deepen ways for the US and India to work together," he said, adding that India's security concerns were the US' security concerns as well.

"India needs a reliable partner on the world stage. I want to make clear: With our shared values and vision for global stability, peace and prosperity, the United States is that partner," he added.

"President Donald Trump and Prime Minister Narendra Modi are committed - more than any of our leaders before them - to building an ambitious partnership that benefits not only our two great democracies, but other sovereign nations working toward greater peace and stability.

"The United States and India are increasingly global partners with growing strategic convergence. Indians and Americans don't just share an affinity for democracy. We share a vision of the future. The emerging Delhi-Washington strategic partnership stands upon a shared commitment (of) upholding the rule of law, freedom of navigation, universal values and free trade."

Mr Tillerson took a swipe at China, saying that while China had been rising alongside India, it had done so "less responsibly, at times undermining the international, rules-based order - even as countries like India operate within a framework that protects other nations' sovereignty".

"China's provocative actions in the South China Sea directly challenge the international law and norms that the US and India both stand for. The US seeks constructive relations with China. But we won't shrink from China's challenges to the rules-based order, or where China subverts the sovereignty of neighbouring countries and disadvantages the US and our friends."

Mr Tillerson repeatedly emphasised prosperity and security in an open Indo-Pacific. "We need to collaborate with India to ensure that the Indo-Pacific is increasingly a place of peace, stability and growing prosperity - so that it does not become a region of disorder, conflict and predatory economics."