The electronic pass has yet to be synced with the IT system being used in the EU to track vaccination statuses, reports The Guardian.
The British government is still awaiting approval on its application to link up with the system, according to reports.
It is understood that “gaps in the UK government’s application to Brussels” is causing the hold-up after it was submitted on July 28.
Once the further technical information required by the EU is provided, it will allow the NHS Covid certificate to link up with the EU system.
This means British holidaymakers and travellers will be able to provide valid proof of vaccination across the EU’s 27 member countries.
But, for now, only around 19 EU countries have officially accepted the NHS Covid pass as proof of vaccination, including popular holiday spots such as Spain and France.
Hungary is one of the countries where Britons may not be able to use their vaccine passport as it will only accept a locally-issued immunity certificate as proof of vaccine status from UK air passengers.
Meanwhile, tourists in Italy, Latvia and the Czech Republic have all reported issues using the app as proof of vaccine status.
The UK government appears to be the only country struggling to gain access to the EU IT system though as other non-EU countries, such as Turkey and Switzerland, have had their applications accepted.
A UK government spokesperson said: “We have applied to link into the EU’s digital Covid certificate (DCC) scheme. We expect the EU’s technical assessment of our DCC application to take a few weeks, as was the case with Switzerland and other states.
“We have had good technical exchanges with the EU commission concerning our application. While the application is considered, member states are still able to decide individually to accept UK Covid certificates.”