PHILADELPHIA (Reuters) - British Prime Minister Theresa May said on Thursday Britain and the United States could look at areas where both could remove some trade barriers to their mutual advantage while she negotiates the country's exit from the EU.

May told reporters aboard a government plane heading to the United States, where she will meet President Donald Trump on Friday, that Britain was limited in how far "we can go in terms of a formal free trade agreement" while still a member of the European Union.

"I think there is much that we can do in the interim in terms of looking at how we can remove some of the barriers to trade in a number of areas. We're able to see an advantage for both of us even if we haven't actually been able to sign that legal free trade agreement," she said.

May also said it was important that the Iran nuclear deal was enforced and that Trump had told her that he was committed to NATO.

(Reporting by Elizabeth Piper; Editing by Chizu Nomiyama)