Marco Rubio visits India this week, with a trip to the world's largest oil refinery topping the agenda

US Secretary of State Marco Rubio kicks off a three-day visit to India on Monday in the finance hub of Mumbai, before heading to Jamnagar, home to a major oil refinery owned by industrial titan Reliance Industries. Rubio's business-oriented visit comes as trade talks remain stalled amid continued ambiguity on punitive measures from the US over India's purchases of Russian oil . Reliance is a top buyer of Venezuelan oil . The refinery can process 1.4 million barrels of crude oil a day, so it's a valuable exporter of diesel fuel for global markets. The refinery has also been a major buyer of Russian Urals crude, making it a significant part of India's energy relationship with Russia.