(Adds Fitch rating on BoE, details)
Dec 9 (Reuters) - Fitch Ratings affirmed the United Kingdom's long-term foreign and local currency issuer default ratings at 'AA', with a negative outlook, citing a wide range of possible outcomes over Brexit negotiations.
"...a key uncertainty is whether it (Brexit agreement) will include a transition arrangement that would provide some stability regarding trading arrangements ahead of the negotiations of a potential future free trade agreement between the UK and the EU," Fitch said in a statement on Friday.
The ratings agency said it expects the UK to invoke Article 50 of the Lisbon Treaty by end-March 2017, which will see the country leave the EU two years later.
The referendum vote to leave the European Union has brought in a period of heightened political, economic and institutional uncertainty, Fitch said.
The ratings agency also affirmed the Bank of England's long-term issuer default rating at 'AA' on Friday, aligning its rating with that of the UK government's. (Reporting by Abinaya Vijayaraghavan in Bengaluru; Editing by Shounak Dasgupta)