The Civil Aviation Authority (CAA) on Friday issued a warning to some foreign airlines for “sudden cancellation" of flights to and from Pakistan, causing hardships to passengers.

The airlines had scheduled extra flights and taken bookings to Pakistan, presuming ease of travel restrictions by authorities. However, they had to cancel them when the National Command and Operation Centre (NCOC) maintained its travel curbs — to allow 20 per cent of the normal air traffic from all over the world with a few exceptions.

In a tweet later in the day, the CAA said it had taken "serious notice" against Qatar Airways, Turkish Airlines, Emirates, Etihad Airways and Fly Dubai for "causing inconvenience to passengers by flight cancellations in recent weeks".

The NCOC had on June 27 announced to increase the capacity for only direct international inbound flights from Europe, Canada, the United Kingdom, China and Malaysia to 40pc of the normal volume of passengers from July 1.

However, some international airlines cancelled flights to Pakistan without prior intimation to the CAA, prompting the authority to take notice and issue warnings to them.

Passengers irked by the flight cancellations had also taken to social media to vent their anger on the issue.

Meanwhile, an official of Qatar Airways told Dawn that some of its flights had been cancelled to comply with the NCOC’s restrictions [on capacity].

The NCOC, in its statement, said it had developed an integrated system to prevent spread of the Covid-19, and in this regard, inbound flights were subjected to routine testing and quarantine of passengers upon arrival, if they were tested positive for the disease.

"So far, 280,000 people who landed home from abroad have been tested, and 600 were quarantined after being found positive for Covid-19," the NCOC said.

An official of the Ministry of National Health Services (NHS) had said Pakistan had introduced three categories — A, B and C — in October last year to deal with Covid-19.

“The countries in category A are exempted from the mandatory coronavirus testing, those in category B require a negative PCR test that has to be taken 72 hours before travel, while people coming from countries in category C have to face restrictions and are only allowed under strict NCOC guidelines,” he had said.

Pakistan had revised travel restrictions for inbound passengers from countries in category C in the second week of June, allowing Pakistanis to travel without the exemption letter. However, foreigners need the letter as per restrictions.

Passengers transiting through category C countries (not leaving the airport premises) also don't require an exemption letter irrespective of the country of origin.