"Congratulations to @theresa_may on taking over as the new UK PM. Looking forward to working with her for stronger India-UK ties," Modi tweeted.
He also praised the outgoing Prime Minister David Cameron, saying he had contributed significantly in strengthening the India-UK ties.
"I also appreciate the significant contribution of @David_Cameron in strengthening India-UK ties," Modi added.
59-year-old May yesterday became Britain's second woman Prime Minister after Margaret Thatcher.