Passports needed for ferry passengers travelling between UK and Ireland
Previously, passengers were able to use other forms of ID, such as driving licences and national identity cards.
Passports will be required for ferry passengers travelling between the UK and Ireland
The changes are being introduced to comply with UK Border Force rules.
From Monday, passengers travelling on ferries between the UK and Ireland will have to show a passport.
Irish Ferries said the new rule applies to its Dublin to Holyhead and Rosslare to Pembroke services, in both directions.
Stena Line said all passengers travelling from Dublin, Holyhead, Fishguard or Rosslare ports will also need to present a valid passport at check-in.
Until now, passengers could use other forms of identification, including driving licences and national identity cards, but the changes are being brought in to comply with UK Border Force rules.
In a statement on its website, Stena Line said the change would satisfy UK Border Force requirements "in relation to the accuracy and integrity of passenger data before boarding".
Irish Ferries said the requirement would apply to all passengers, including Irish and UK citizens, and added that from Monday, driving licences, national identity cards and other forms of photographic identification would no longer be accepted on the two routes concerned.
Irish Ferries said passengers who were not British or Irish citizens and were visiting for a short stay of up to six months in the UK may need an Electronic Travel Authorisation (ETA), which allows travel to the UK, Jersey, Guernsey or the Isle of Man for up to six months.
Passport cards will also be accepted by both operators.