Standard & Poor’s has warned that it may downgrade the triple A rating of the 27-nation European Union, just as the leaders of the bloc head towards Brussels for a crucial summit.

In a statement on Thursday, the ratings agency said it was placing the EU’s AAA long-term rating on so-called creditwatch negative.

The warning comes just days after S&P put a large number of the 17 euro countries on notice for a possible downgrade, including Germany and France.

S&P said it hopes to conclude its assessments on the eurozone countries as soon as possible after the Friday summit. Following this, it expects to resolve its action on the EU as a whole.