Ryanair is being investigated by the UK's competition watchdog over charges it imposes on parents to sit next to their child on flights.

The Competition and Markets Authority (CMA) said it was looking into whether the airline's policy, which the watchdog said typically led to a fee of £8 each way, was "unfair" under consumer law.

It said Ryanair's terms and conditions state a parent must sit with their child if aged between two years and 11, and this is done through what the airline calls a "mandatory family seat" that the parent must pay a fee for.

Ryanair called the investigation "bogus" and insisted its family seating policy "fully complies with all relevant laws".

The CMA is looking at whether the airline's "approach to seat reservations may mean parents are being charged for the airline to meet its child safety and disability‑related obligations as set out under aviation rules – and will investigate to determine whether or not this practice is in line with consumer law".

The watchdog said it understood that Ryanair was the only major airline flying from the UK to impose such a charge.

It said other airlines offered to seat children next to a parent or guardian without a fee, or allocate seats together automatically during booking for free.

The CMA added that its investigation had just started, and it had "reached no conclusions about whether Ryanair has broken the law".

Ryanair said adults travelling with children pay one reserved seat fee, "but can select reserved seats beside them for up to four children on the same booking FREE OF CHARGE".

"This means that parents travelling with children pay for only one (adult) reserved seat but pay nothing for the four other reserved seats for their children travelling with them," it added.

"This bogus CMA investigation is a failed effort by the Starmer Govt to pretend it cares about consumers when it has failed to abolish APD [Air Passenger Duty] which would immediately deliver lower fares for all consumers and growth for the UK aviation, tourism and wider economy.

"Ryanair looks forward to disproving these false CMA claims during this bogus investigation."

The CMA said it would also examine whether "the mandatory family seat fee is 'dripped' during the booking process and whether consumers are presented with the total price that they will pay".

The CMA's director of consumer protection, Hayley Fletcher, said extra charges can quickly bump up the price for families saving up for an affordable summer holiday.

"Our investigation will consider Ryanair's approach to family seat reservations and how the cost is presented to consumers to determine whether they comply with consumer law.

"For the past year, we've told businesses to ensure their customers are shown the total price upfront – those who don't face the very real possibility of action from the CMA."

Consumer rights body Which? welcomed the investigation.

"Which? has repeatedly highlighted Ryanair's harsh approach to separating families and making parents pay a fee to sit next to children as young as three," said Rory Boland, travel editor at Which?, "so it's good to see the regulator investigating the airline's behaviour."

He added: "Ryanair doesn't have to wait for the outcome of the CMA's investigation, it could stop charging these unreasonable fees today and we would encourage them to do that."

The investigation is part of the CMA's wider aims to help ease cost of living pressures. Under new powers, it can fine companies up to 10% of their global turnover if they breach consumer law.