New Delhi, May 21 : Centre on Thursday said that limited passenger flight operations of about one-third of capacity would be permitted to operate from May 25. In a general set of guidelines for passengers and stakeholders issued by the Ministry of Civil Aviation, the Centre said: "On the day of commencement, limited operations (about l/3rd) would be permitted." "Further augmentation of flights will be done in a calibrated manner." The guidelines advised "Vulnerable" persons, such as very elderly, pregnant ladies, passengers with health issues to avoid air travel. Furthermore, it detailed that no physical check-in counters would be allowed at the airport. "Only those passengers with confirmed web check-in shall be allowed to enter the airport," Besides, the Centre advised the airlines to adhere to the lower and upper limits of fares prescribed by the Ministry during the period of COVID-19 pandemic. The guidelines comes a day after Civil Aviation Minister Hardeep Singh Puri on Wednesday said: "Domestic civil aviation operations will recommence in a calibrated manner from Monday, 25th May 2020." "All airports and air carriers are being informed to be ready for operations from 25th May," he said. Furthermore, the minister said the standard operating procedures (SOPs) for the passenger movement would be issued soon. Ever since the imposition of the nationwide lockdown in the wake of the coronavirus outbreak in the country on March 25, passenger air services were suspended for both scheduled domestic and international flights. /IANS