Gadgets and clothes were missing from the registered luggage of three passengers who flew to Calcutta, though the locks were intact. Two of them lodged complaints with Air India Express on Thursday.

The duo were part of a seven-member delegation of a voluntary organisation that travelled to Bangkok last week to attend a convention. After landing at Netaji Subhas Chandra Bose International Airport on Tuesday, they had to wait for nearly an hour to collect their bags.

“There was a combination lock and another lock on my bag. Both were in place,” said Pradip Chatterjee, an engineer working with the Durgapur Municipal Corporation and a part of the group.

After reaching his home in Durgapur, he failed to find “two new cellphone sets purchased in Bangkok and a digital camera”. The case of one of the phones was in the bag.

Chatterjee emailed a complaint to the airline and called up its office. “They told me that since I had detected the theft after leaving the airport, they could not do anything,” he said. “Why should I check the contents of my bag when the locks are intact?”

Deepak Sau, an income-tax lawyer from Purulia and another member of the delegation, also could not find his digital camera and a new cellphone.

“Even the security tape around the bag was in place. So there was no reason to be suspicious. But after reaching home, I could not find the items,” said Sau.

An airline spokesperson said the officials were cooperating with security agencies to crack the “mystery”.

Abhay Singh (name changed on request), a city-based businessman, had a similar experience last week. When he received his bag at the airport after coming back from Hong Kong, he found that it had been broken into and clothes had been taken out.

After he lodged a complaint with the private airline, he was told that the bag was damaged by mishandling but there was no theft.

According to airport officials, complaints of theft from passengers arriving at the airport have increased in the past few months.

“Baggage handling has been outsourced to agencies. The luggage segregation area is congested with bags and sometimes, the handling employees take advantage. Usually, bags without locks are targeted,” said an official.

The thefts need not necessarily have taken place in Calcutta. A security official said the items could have been stolen at the airports where the passengers boarded the flights or even in transit.