Malta is among the countries which would most suffer the consequences of a UK exit from the European Union, according to ratings agency Fitch.
The most exposed countries would be Ireland, Malta, Belgium, the Netherlands, Cyprus and Luxembourg, all of whose exports of goods and services to the UK are at least eight per cent of GDP, the agency said.
"The economic impact of Brexit would be lower for the EU than for the UK, but would still be palpable. It would reduce EU exports to the UK, although the extent would depend on the nature of any UK-EU trade deal and the degree and duration of sterling depreciation."
Fitch said countries could gain from the shift of some FDI from the UK to the EU. However, countries such as Luxembourg, Malta, Belgium and Germany, with a large stock of foreign direct investment and financial assets in the UK, would suffer losses in the euro value of those assets if there were a permanent depreciation of sterling.
The banking sectors of Ireland, Malta, Luxembourg, Spain, France and Germany have sizeable links to that of the UK.
Brexit could boost anti-EU or other populist political parties
In its report, Fitch said an EU exit by the UK would weigh on the economies of other member countries and increase political risks in Europe.
"We would not expect to take any immediate negative rating actions on other EU sovereigns if the UK left. But negative actions would become more likely in the medium term if the economic impact were severe or significant political risks materialised."
Brexit would reduce the UK's contribution to the EU budget (a net €7.1bn in 2014 after rebates) potentially to zero. This would imply that other net contributors would have to increase payments, or net recipients accept lower EU expenditure.
Brexit would create a precedent for countries leaving the EU. It could boost anti-EU or other populist political parties, and make EU leaders more reluctant to implement unpopular policies with long-term economic benefits. Negotiating the terms of the UK's exit could exhaust the EU's time and energy and open up new fronts of disagreement.
Brexit could shift the centre of gravity of the EU, making it more dominated by the eurozone core, poorer, more protectionist and less economically liberal. If the UK were to thrive outside of the EU, it might encourage other countries to follow suit.
Fitch said Brexit could precipitate Scotland leaving the UK, which might intensify secessionist pressures in other parts of the EU, such as Catalonia in Spain.