Ryanair's dual citizen passengers may be allowed to board flights to the UK without exactly the right documents so long as they have valid proof of their citizenship, amid confusion over new rules.

The carrier has indicated that it might permit British dual nationals to board UK-bound flights without certain documents from next week, when new, somewhat confusing regulations take effect.

From next Wednesday, dual nationals have been instructed that they must show a British passport when travelling to the UK, or secure a "certificate of entitlement" costing £589. Currently, they can enter using non-British passports.

The new regulation applies to all dual British nationals regardless of where they reside. The Home Office has instructed airlines to refuse boarding to any dual national who does not possess a British passport, including children.

However, concerns have been raised about the confusing nature of the new regulation and worries that British citizens would be left stranded outside the country. Ryanair was asked if dual nationals would be permitted to board if they presented a foreign passport without an electronic travel authorisation (ETA) - the new visa-waiver scheme - and also had evidence of British citizenship.

Are you worried about being impacted by the new rules? Email webtravel@reachplc.com

• Spain's 'ghost islands' deliberately cut off from the mainland to keep tourists out

• Former air crash investigator reveals safest seat on a plane and it's not 11A

In response, a spokesperson for the company said: “Yes, we will allow a passenger to board a flight to the UK if we are satisfied that the passenger is a British national, an Irish national or is in possession of any other status in the UK, including passengers who hold an old stamp/vignette with indefinite leave to remain."

Cabin crew might point passengers in such a position to a UK government carrier support hub that could help verify passengers’ identities and eligibility to travel. If the verification goes ahead, dual citizens may be able to fly.

It is understood that other airlines could do similar.

From February 25, visitors to the UK will need an Electronic Travel Authorisation (ETA). Those without an ETA will not be able to board their flight, ferry or train. British and Irish citizens, including dual nationals, are exempt from this requirement, but they will have to meet other requirements.

In order to travel to the UK, dual nationals will now need a valid British passport. Alternatively, they can pay £589 for a certificate of entitlement to attach to their second nationality passport. Dual nationals have previously been able to enter the UK using their non-British passport without cost.

Dual nationals who try to enter the UK using only a foreign passport could face complications. British citizens have a statutory right of abode in the UK, but travellers might be subject to additional checks while their status is verified. They could also be stopped from boarding if they cannot prove their right of entry.

The Government announced the rules last year, but some dual nationals have said the changes have been brought in at short notice and were poorly communicated. There are fears that holidays or work trips could be affected if people cannot get a passport or certificate of entitlement in time.

• Ryanair summer holidays flights to Spain from £23

• TUI launches new route to gorgeous city that looks like nowhere else in Spain

People affected have said the rule changes make them feel like “second-class citizens”, arguing that they will be put in a worse position than foreign citizens, who can travel to the UK on their foreign passport and a £16 ETA.

Luke Petherbridge, Abta’s director of public affairs, urged the government to introduce a grace period, during which carriers should be allowed to let people board with alternative proof of citizenship, as Ryanair has said it will.

A Home Office spokesperson said: "We recognise that this is a significant change for carriers and travellers, but we have been clear on requirements for dual British citizens to travel with a valid British passport or Certificate of Entitlement, in line with those for all British citizens.

"At their own discretion, carriers can accept an expired British passport as alternative documentation. Separately, individuals who have previously had a British passport can apply for an emergency travel document if they urgently need to enter the UK. In line with current practice, on arrival at the UK border, Border Force will still assess a person’s suitability to enter the UK and conduct additional checks if required."

The Home Office has confirmed that the new rules apply to children and babies, even if they are travelling with a parent who has a British passport. However, Border Force agents will have “discretion” about whether to allow them in.

Ensure our latest lifestyle and travel stories always appear at the top of your Google Search by making us a Preferred Source. Click here to activate or add us as your Preferred Source in your Google search settings.