DUBLIN, March 4 (Reuters) - The European Union's finance chief said Britain's decision to make unilateral changes to Northern Irish Brexit arrangements raised questions over whether it can be trusted in future trade negotiations with any partner.

"It does open a question mark about global Britain, if this is how global Britain will negotiate with other partners. Our experience has been not an easy one to put it mildly," Mairead McGuinness, who is negotiating post-Brexit financial services terms with Britain, told Irish broadcaster RTE on Thursday.

"We have to be very clear that when something happens that is not appropriate and indeed in our view breaches both trust and an international agreement, then we have to call it out. It wasn't a good day yesterday but this morning we have to work for practical solutions, with the UK, not separately." (Reporting by Padraic Halpin; editing by John Stonestreet)