Ratings agency Fitch said today that Prime Minister Theresa May's timescale for reaching a post-Brexit trade deal with the European Union was "ambitious".
The rating agency also said that the uncertainty would weigh on Britain's credit rating.
"We will continue to focus on the degree to which the Brexit process risks damaging UK medium-term economic prospects and public finances," Fitch said in a statement in response to the major speech from May yesterday.
"The range of possible Brexit outcomes remains wide and the envisaged timescale for reaching a UK-EU trade agreement ambitious," it added.
The British Prime Minister said she hopes to reach a trade agreement during the two years of formal talks to leave the EU which she plans to start within two or three months.
Fitch downgraded Britain's credit rating to 'AA' with a negative outlook after June's Brexit vote.
