The US embassy confirmed the executive order is being implemented at two Irish airports
An Executive Order issued by President Donald Trump banning nationals of seven Muslim-majority countries for three months and stopping the admission of all refugees for four months is in effect in Ireland.
The order - which also bans those fleeing from Syria from entering the US indefinitely - has been implemented by US Customs at Dublin and Shannon airports, the United States Embassy confirmed
A note on the US Embassy website says that nationals of the countries listed on the Executive Order who have already scheduled a visa interview in Dublin, should not attend their appointment, as the Embassy will not be able to proceed with the interview.
The statement adds that the embassy will announce any additional changes affecting travellers to the US as soon as that information is available
Meanwhile, New York immigration lawyers have moved to block the order saying numerous people have already been detained and many others turned away.
Technology giant Google has also urged around 100 employees to return as soon as possible from abroad, for fear they could be affected.
Debbie Almontaser from the Muslim Community Network said the impact of the Executive Order will be "immense".
"We fear it will further marginalise communites", she said.
During his weekly address, President Trump insisted his reforms are justified, saying his administration "will never ever stop fighting for the American people".
"This administration has hit the ground running at a record pace", he said. "We are doing it with speed and we are doing it with intelligence."
UK Prime Minister Theresa May has refused to condemn President Trump when asked by Sky News about his new ban on refugees and controls on travellers from seven predominantly Muslim countries.
The Prime Minister tried to avoid commenting on the controversial policy during a news conference with her Turkish counterpart Binali Yildirim.
On Friday Mrs May became the first foreign leader to visit the White House since Mr Trump's inauguration - and talked stateside about their shared values.
The new controls were announced after the PM left Washington DC and she was asked by Sky News whether she still believed she shared the values of President Trump.
But while Mr Yildirim criticised the visa restrictions, Mrs May at first dodged the question.
She said: "I was very pleased to visit Washington and hold the discussions I did with President Trump yesterday.
"On the issue of refugees I've recognised the contribution Turkey has made in hosting and supporting three million refuges as a result of the Syrian conflict.
"The UK also has a good record in that we have developed a number of schemes for resettlement from the region.
"The UK is the second largest bilateral donor outside the region in terms of money we've put into this issue."