India hailed its "strategic" partnership with oil-rich Saudi Arabia on Monday, days after unveiling a major trade and transport route linking Europe, the Middle East and India as part of a broad alliance.

"Together, we made the historic start to establish an economic corridor," Indian Prime Minister Narendra Modi told Saudi Arabia's de facto ruler Crown Prince Mohammed bin Salman in New Delhi.

On Saturday, the pair took part alongside other G20 leaders in the unveiling of ambitious plans to create a modern-day Spice Route, boosting trade ties with potentially wide-ranging geopolitical implications.

"This corridor will not only connect the two countries, but economic cooperation, digital connectivity between Asia, West Asia and Europe," Modi added, in talks following the end of the two-day Group of 20 leaders' summit he hosted.

India and Saudi Arabia, along with the United States, the European Union, the United Arab Emirates and others launched the initiative to link railways, ports, electricity and data networks and hydrogen pipelines.