Britons have been warned of major airport delays while travelling to Portugal during July and August.
Industrial action by baggage handlers has caused disruption that could last weeks while travelling to the European tourist hotspot.
The updated information from the Foreign, Commonwealth & Development Office (FCDO) also applies to Madeira, Porto Santo and the Azores.
British tourists are advised to check for announcements and follow the advice of their airline or tour operator.
Travellers are warned to read up on the latest safety and security advice whilst visiting the Southern European destination.
There is a high threat of terrorist attack globally affecting UK interests and British nationals, including from groups and individuals who view the UK and British nationals as targets, according to the FCDO.
Demonstrations, political gatherings, and marches are said to not be uncommon, particularly in urban areas.
Despite crime rates being low, pickpocketing, bag-snatching and theft from holiday properties are common in major tourist areas.
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PA | Britons have been warned of major airport delays while travelling to Portugal during July and August
The UK Government highlights that care should be taken on public transport and at busy stations and crowded bus and tram stops to avoid being a victim of theft.
Foreign-registered and rental vehicles are particularly targeted, with criminals sometimes employing threats or violence during thefts.
Britons are also told to check that their holiday accommodation is secure and to lock all doors and windows at night and when they go out.
Visitors have been advised to carry identification at all times, as Portuguese police and judicial authorities can request to see documents.
GETTY | The updated information from the Foreign, Commonwealth & Development Office (FCDO) also applies to Madeira, Porto Santo and the Azores
A passport photocopy may suffice, although officials may require the original.
Like many Mediterranean destinations, wildfires pose a heightened danger during the summer months, from April to October.
The updated warnings follow the popular Portuguese holiday destination of Albufeira issued a Code of Conduct which bans inappropriate behaviour in public places.
The top fines, published a month ago, aim to crack down on illegal activity, with full nudity in public and sexual acts or simulation in public landing tourists with the maximum fine.
FCDO | The 15 new rules that could see Britons travelling to Albufeira fined up to £1,500Partial nudity in public, drinking alcohol in the streets and urinating in public places could see travellers forced to pay a fee of nearly £1,300.
Other offences with fines of over £1,000 include excessive noise and damaging municipal property.
Minor offences can still result in Britons facing heavy fines.
These include sleeping in public, spitting on the ground, cooking in public places and the misuse of public furniture.