The new 'strictly enforced' UK border rule every dual citizen needs to know

A big change is coming for Australian-British and Australian-Irish dual citizens travelling to the UK.

Australian-British and Australian-Irish dual citizens will soon need to enter the UK using their British or Irish passports, after the UK government confirmed the rules would be "strictly enforced".

From February 25, dual citizens will no longer be able to obtain an Electronic Travel Authorisation (ETA) or a visa to enter the UK and may be refused boarding without the correct documentation, according to a Smartraveller warning.

The move reflects a tightening of enforcement around the UK's ETA scheme, which applies to most non-UK and non-Irish passport holders.

Australians travelling on an Australian passport alone must apply for an ETA, while dual British or Irish citizens must travel on their UK or Irish passports.

Alternatively, dual citizens can use a certificate of entitlement to the right of abode, an official document linked to another valid passport.

The tightening of entry rules comes as Australian families could be forking out hundreds of extra dollars to visit the UK due to a new tourist tax.

The UK government has passed legislation allowing British mayors to introduce a "modest" nightly tourist tax that would apply to overnight stays.

The levy will apply to paid accommodation for tourists such as in hotels, guesthouses, campsites and holiday letting platforms such as Airbnb.