A major change of rules for ferry passengers crossing the Irish Sea should also apply to Northern Ireland, Sinn Féin has said.

Ferry passengers between Ireland and Britain will need a valid passport from the end of next month, according to the requirements of the UK Border Force.

Stena Line and Irish Ferries informed customers on Wednesday that the change is due to UK Border Force rules on “accuracy and integrity of passenger data before boarding”.

Currently, passengers are not always asked to show a passport but are sometimes required to have another form of photo ID.

Under the century-old Common Travel Area agreement, Irish and British citizens do not legally require a passport to travel between Ireland and Britain.

However, certain airlines have required a passport for boarding and the measure for ferries comes into effect from Monday September 28.

Ferry operators say routes between Britain and Northern Ireland will not be affected by the changes.

Sinn Féin justice spokesman Matt Carthy said improved passenger information and data between the island of Ireland and Britain “makes sense”, but he said it should also include travel from Britain to Northern Ireland.

He said: “Tightening passenger verification requirement on some but not all ferry travel between Britain and Ireland makes little sense.

“Sinn Féin wants to see progress towards enhanced data sharing on travel within the Common Travel Area, improved passenger verification, and the development of all-island migration management policies that should include the development of measures such as an all-Ireland entry-exit scheme in the future.”

Stena Line said all passengers travelling between Holyhead and Dublin or Fishguard and Rosslare will now need to show a passport on departure and no other forms of ID will be accepted.

It said the rule applies to all passengers regardless of age or nationality.

It added: “Customers with existing bookings are currently being notified by the customer service team to ensure customers are fully supported during this change of operations.”

There is no change to the ID requirements for business or leisure passengers travelling with Stena Line from Belfast, Liverpool, Cairnryan or Heysham.

In a similar statement, Irish Ferries said: “All passengers, including Irish and British citizens, travelling between the Republic of Ireland and Britain (both directions) will be required to carry a valid passport.”

The operator encouraged all passengers to check they have an in-date passport or passport card before arriving at the port.

Mr Carthy also wants the Dublin Government to pursue an agreement with London to ensure applicants for international protection “who should have their asylum claims assessed there are returned in a timely manner”.

The UK Home Office and the Irish Departments of Foreign Affairs and Justice have been contacted for comment.