An airline accused of asking passengers to pay extra for fuel to fly home has cancelled UK flights at the weekend.
A Comtel Air flight from Amritsar to Birmingham was grounded in Vienna on Tuesday by its Spanish carrier Mint Lineas Aereas due to financial issues.
Passengers said they were "held to ransom" and asked to pay a total of £23,000 to continue their journey.
Comtel majority shareholder Bhupinder Kandra said money paid to travel agents had not been passed on to the airline.
One of the travel agencies selling seats on the flight, Astonbury Ltd, trading as Skyjet UK, has announced it has ceased trading.
The Essex-based company was registered with the Air Travel Organisers' Licensing (Atol), run by the Civil Aviation Authority (CAA) in the UK.
The CAA said it would be stepping in to "assist repatriation for all customers", and estimated 200 Skyjet UK customers were currently abroad.
It added that passengers who had not yet travelled would be able to claim a full refund via the CAA.
BBC India Correspondent Sanjoy Majumder said several hundred passengers in India were thought to be affected by the cancelled flights.
"It's quite hard getting a handle on the exact number. Most of them have links to the area. Most of them are staying at relatives' homes.
"This was an airline that had a flight every single day from Birmingham to Amritsar," he said.
Birmingham Airport confirmed the flight cancellations and said anyone due to travel should contact their agent.
One of those held up in Vienna, Kulveer Singh, from Wolverhampton, said passengers had been "effectively held to ransom".
"Passengers were lending money to each other to make sure we could take off. We were so desperate. It had been four days at that point.
"I am diabetic and ran out of insulin the day after the flight first got cancelled. I had to watch what I ate until I could locate a medical shop which had an insulin pen I could actually use.
"I was lucky there were other diabetics on the flight and we could look out for each other," he said.
Daljit, from West Bromwich, said her mother and brother were among the passengers grounded during refuelling in Vienna on Tuesday.
She said: "They did make it back after paying £130 each while they were stuck in Vienna.
"They should have got back here on Saturday, that was the original date to come back, and my brother had to start work on Monday so he's lost that because he didn't make it back on time."
Sue Ockwell, a crisis management expert at Travel PR, said the situation was highly unusual in Europe, where airlines are tightly regulated.
"It's a bit like, well, boarding a train and saying that you can't go on because they've cut the electricity off because they haven't paid the bill," she said.
Staying with relatives
Amarjit Duggal told the BBC that she flew from Amritsar last week after scattering her mother's ashes.
She said her father, sister and uncle were still there and did not know when they would be able to return home.
In October the Austrian-registered airline contracted the Spanish carrier firm Mint Lineas Aereas (MLA) to operate a service between Birmingham and Amritsar.
The airline said on Thursday it was owed money by English travel agents along its supply chain, which is why it had not paid MLA since last month.
In a statement on Thursday, MLA said: "Due to unresolved financial questions, it was decided by Mint Lineas Aereas as operating carrier to stop operations for Comtel Air."
The British High Commission said on Thursday it was not aware of any Birmingham-bound Comtel Air passengers who were stranded at the airport in Amritsar.
Sanjoy Majumder said many of the passengers due to fly back to the UK were thought to be staying with friends or family, rather than waiting at the airport.
He added that the Indian and British authorities had advised passengers to buy tickets on commercial airline flights over the weekend, most of which were more expensive than their original tickets.