Fitch affirms UK's sovereign rating at AA+
The credible macroeconomic policy framework and sterling's international reserve currency status also underpins the ratings.
Fitch assessed that a vote to leave the EU after the referendum on June 23 would be a moderate credit negative for the UK, affecting its medium-term growth and investment prospects and its external position.
"In the event of a 'Leave' vote, and as we have guided previously, we would review the UK's ratings shortly after the referendum result," Fitch said.
The agency expects gross domestic product growth to be 1.9 percent this year and 2 percent in 2017 and 2018.
The stable outlook reflects Fitch's assessment that upside and downside risks to the ratings are currently balanced. ■