Air India on Monday night barred 19 Indian students from boarding its flight to San Fransisco so they are not "inconvenienced" after being told by the US authorities that the two universities to which they had secured admission were under "scrutiny".

The national carrier, which did not allow these students to board the flight at Hyderabad's Rajiv Gandhi International Airport, has decided not to accept students headed to these universities till the time it got clearance from Air India's US office for their travel.

"Air India received communication on December 19, 2015 from the US Customs and Border Protection agency that two universities namely Silicon Valley, San Jose, California and North Western Polytechnic College, Fremont, CA are under scrutiny and students who arrived into San Francisco were not allowed to enter the US and were deported back to India," an Air India statement said.

"In the past, we have witnessed that students who secured admission in those institutions have been deported to India as soon as they land there. To avoid embarrassment to them and save their money, we prevented them from boarding the flight," an AI official said in Hyderabad.

Air India has offered full refund and waived all charges such as cancellation and rescheduling fee.

The airliner said it will start accepting students travelling to join these universities, at no additional cost, as soon as clearance is received from Air India's US office.

The statement said so far 14 students who travelled on Air India flights to San Francisco have been deported. Students travel on a one-way ticket to the US and, in the event of deportation, incur huge expenditure to buy a ticket back to India on first available service. Further, seats are often not available on any airlines to travel back," it said.

"Considering the situation, as a precautionary measure and to avoid inconvenience, students booked for travel to take admission to these universities are not being accepted on Air India flights," the statement said.

US Consulate officials in Hyderabad said they are trying to gather information on the episode.

"We are indeed aware of the reports that some students were denied entry on the flights to the US. At this time, we don't have any further information to share with you on this particular issue, but we are seeking clarity on the situation.

"As soon as we have new information, we will get back to you immediately," an email reply from the US Consulate said.

When contacted, an immigration official at the Rajiv Gandhi International Airport said that clearance for boarding a flight has to be given by the airline concerned through the issuance of boarding pass.

"The students were not issued boarding passes. It is the airline's responsibility to clear passengers. We have nothing to do with the issue," he said.