DUBLIN, Nov 30 (Reuters) - Ireland will require all arrivals to have proof of a negative COVID-19 test - regardless of their vaccination status - to slow the potential spread of the new Omicron coronavirus variant, the government announced on Tuesday.

Ireland is studying 11 suspected Omicron cases after initial tests showed they had a trait distinct from the dominant Delta variant. Health Minister Stephen Donnelly said it is likely the new variant is present in the country.

Passengers who are fully vaccinated or who have been infected during the past 180 days will be required to have a negative lab-conducted antigen test taken no more than 48 hours before arrival or a PCR test no more than 72 hours before arrival, the government said in a statement.

Other arrivals will be required to show a negative PCR test.

The new rules, which come into effect on Friday, will apply to arrivals from Britain but not across the open border with Northern Ireland. Ireland and Britain share a common travel area and similar rules introduced by London last week do not apply to passengers from Ireland. (Reporting by Padraic Halpin and Conor Humphries; editing by Barbara Lewis and Emelia Sithole-Matarise)