MOSCOW (Sputnik) — The referendum on EU membership could also increase Britain’s deficits and private short-term external debt, the ratings agency added.
"The outlook revision reflects our view that the decision of the newly elected Conservative majority government to hold a referendum on the UK's EU membership by 2017 represents a risk to growth prospects for the UK's financial services and export sectors, as well as the wider economy," S&P said in the statement.
The Conservative Party's strategy could also affect Britain’s long-term economic prospects "more than previously anticipated," the service said.
As long as the United Kingdom is a member of the European Union, the country could receive a more positive external assessment, even despite its high external debt, S&P concluded.
In the run-up to the UK May 7 general elections, the issue of Britain's membership in the European Union became hotly-discussed. After the election victory, British Prime Minister and Conservative Party leader David Cameron reaffirmed his commitment to holding a referendum on membership in the bloc by the end of 2017.