NEW DELHI: India's biggest diplomatic battle since the nuclear deal has begun in earnest — New Delhi has quietly submitted its formal application for membership of the Nuclear Suppliers Group ( NSG ) ahead of PM Narendra Modi's visit to the US starting June 4.

The application was pushed through on May 12, almost a week before Pakistan sent its case. And the first big test will be on June 9-10 at a closed-door NSG meet in Vienna.

Senior diplomats, who didn't want to be identified, said  that the Indian Prime Minister himself has been burning the telephone lines, reaching out to heads of government across the 48-member body to pitch for India's case.

The submission of the application, which comes after nearly seven years of talks with NSG and its various forums, has set Modi regime up for a big fight with China, an NSG member that is batting for Pakistan, a report in Times of India said Friday.

The process began in last week of April when India transmitted what is called the 'adherence to NSG' document to International Atomic Energy Agency. This lists all the laws and rules that have been changed or inserted to streamline India's regime in line with NSG guidelines. India submitted its application on May 12.

Now, big diplomatic push will come from the PM when he goes to the US on June 4. New Delhi is counting on Washington to send out a strong and clear message that will set the tone for the crucial NSG technical meet on June 9-10, where India's application will be assessed. The action will then shift to the June 24 NSG plenary in Seoul, where the case is likely to be put up on the agenda.