British Airways is facing a backlash from passengers after forcing them to pay extra to guarantee sitting with their family on flights.

Furious travellers complain that they are being split up from loved ones as they head off on holiday.

Worst affected are passengers who have bought the cheapest deals. But even BA's executive club members who have been awarded 'companion vouchers' to go on a romantic break or honeymoon with their partner are being separated on flights.

The only way to ensure a seat with your family is to pay £20 to reserve one on longer flights of five hours or more, or £7 a seat on short-haul flights.

Split up: Furious travellers complain that they are being split up from loved ones as they head off on holiday. Worst affected are passengers who have bought the cheapest deals

Seats by the emergency exit cost £50 to reserve, while executive club members are charged £24 per seat on longer flights.

The policy was introduced in 2009. Paid-for reservations were said to be based on requests from customers – but many are now complaining about the policy on social media, as the airline also faces a backlash for scrapping free sandwiches on short-haul flights and for its plans to reduce leg room on some flights.

Economy class passengers can check in online up to 24 hours before departure.

BA says its computer system then randomly allocates seats for those who do not pay extra. It says this programme aims to sit family and friends on the same booking together. But those who have bought basic fares – where they are only allowed cabin luggage – are given the lowest priority.

Earlier this month Ryanair was accused of deliberately splitting up families to force them to pay extra, which the budget airline denied. But BA customers assumed Britain's flagship carrier was above levying sneaky extra charges.

Slipping: Critics say BA is becoming similar to budget airlines under its Spanish boss Alex Cruz

Passengers have criticised BA on Twitter in recent days. Hannah Nutley wrote: 'So angry with @British_Airways paid £100 to book seats. At checkin seats changed. 3 people now split. On phone 30min+ refused to help.'

Sarah Brovda complained: 'Unable to check in online bec of new system, so couldn't pre-pay to choose seats. Sitting sep from fiance, flight delayed @British_Airways.'

The row will fuel criticism that BA is becoming similar to a budget airline under its Spanish boss Alex Cruz. Its reputation has been badly bruised by last month's IT shutdown, which grounded flights and led to tens of thousands being stranded.

A BA spokesman said: 'We can never guarantee customers will be sat together, especially on very busy flights, and we will always prioritise seating for families travelling with children and customers with special needs. Customers can choose to pay to select specific seats in advance if they wish to do so.'