British travellers still carrying red passports issued with urgent reminder before this summer

UK holidaymakers still using the old red passport have been issued a summer travel warning. If you're planning a sunny getaway this year, it's important to check your passport before you go due to strict entry rules in other countries.

Many countries require your passport to be valid for another six months before you can travel internationally. This is known as the 'six-month validity rule', reports Liverpool Echo.

READ MORE: 'Mystery' £8 beauty box shoppers using as 'birthday gifts for the year' and you can get Elemis

VisaGuide.World states that 70 countries have a six-month passport rule, while another 41 apply the three-month passport validity rule. This means travellers can enter these countries if their passport is valid for at least three more months.

If you still have a red passport, which are no longer being issued after the UK left the EU, it's crucial to check its expiry date. Since Brexit, your passport must be less than 10 years old on the day of arrival in the EU and have at least three months left on the day you plan to leave.

Here are 70 countries with a six-month passport rule:

Afghanistan, Algeria, Anguilla, Bahrain, Bhutan, Botswana, British Virgin Islands, Brunei, Cambodia, Cameroon, Cayman Islands, Central African Republic, Chad, Comoros, Curacao, Cote D'Ivoire, Ecuador, Egypt, El Salvador, Equatorial Guinea, Fiji, Gabon, Guinea Bissau, Guyana., Indonesia, Iran, Iraq, Israel, Jordan, Kenya, Kiribati, Laos, Madagascar, Malaysia, Marshall Islands, Micronesia, Myanmar, Namibia, Nicaragua, Nigeria, Oman, Palau, Papua New Guinea, Philippines, Qatar, Rwanda, Saint Lucia, Samoa, Saudi Arabia, Singapore, Solomon Islands, Somalia, Somaliland, Sri Lanka, Sudan, Suriname, Taiwan, Tanzania, Thailand, Timor-Leste, Tokelau, Tonga, Tuvalu, Uganda, United Arab Emirates, Vanuatu, Venezuela, Vietnam, Yemen, Zimbabwe

And here are 41 countries that have a three-month passport rule:

Albania, Austria, Azerbaijan, Belarus, Belgium, Bosnia and Herzegovina, Czechia, Estonia, Finland, France, Georgia, Germany, Greece, Honduras, Iceland, Italy, Jordan, Kuwait, Latvia, Lebanon, Liechtenstein., Lithuania, Luxembourg, Malta, Moldova, Monaco, Montenegro, Nauru, Netherlands, New Zealand, North Macedonia, Norway, Panama, Poland, Portugal, Senegal, Slovakia, Slovenia, Spain, Sweden, and Switzerland.

Countries with other validity rules:

Bermuda (45 days upon entry), Eritrea (three months on arrival), Hong Kong (three months on arrival), Lebanon (three months on arrival), Macau (three months on arrival), Micronesia (four months on arrival), South Africa (three months on arrival), The Maldives (three months on arrival), and Zambia (four months on arrival).

See more accommodation options on Booking.com and Hotels.com. You can book UK and European trains - including cheap Eurostar tickets - on Trainline. Book flights on Skyscanner, EasyJet or British Airways.