US President Donald Trump greeted Prime Minister Narendra Modi on his 70th birthday, praising him as a "great leader and loyal friend".

Prime Minister Modi, born on September 17 in 1950, turned 70 on Thursday.

"I would like to extend best wishes and a very happy 70th birthday to the Prime Minister of India, @narendramodi. Many happy returns to a GREAT LEADER and loyal friend!" Trump tweeted Thursday afternoon local time.

He also posted a photograph of him and First Lady Melania Trump with Prime Minister Modi at the 'Namaste Trump' event. The two leaders had their hands raised and clenched before a 125,000-strong crowd who had gathered to welcome the US president on his first India visit at Motera Stadium in Ahmedabad in February this year.

At the event, Prime Minister Modi had said that a "new history" was being created.

Trump was among a host of world leaders, including Russian President Vladimir Putin, British Prime Minister Boris Johnson and German Chancellor Angela Merkel, who wished Modi on his birthday and lauded him for strengthening ties with their countries.

Putin and Merkel wrote letters to Modi, and Johnson and several others tweeted.

Modi responded individually to many of those who wished him on Twitter.

"People from all over India, from all over the world have shared their kind wishes. I am grateful to each and every person who has greeted me. These greetings give me strength to serve and work towards improving the lives of my fellow citizens," he said in one of his tweets late night.

The prime minister also urged people to take precautions to defeat the coronavirus.

"Since many have asked, what is it that I want for my birthday, here is what I seek right now: Keep wearing a mask and wear it properly. Follow social distancing. Remember 船o Gaj Ki Doori.' Avoid crowded spaces. Improve your immunity. Let us make our planet healthy," he said.