Solving the eurozone crisis is "beyond reach" politically and technically, according to a credit rating agency.
Fitch warned Spain, Italy, Belgium, Slovenia, Ireland and Cyprus they were at risk of their debt being downgraded late on Friday night as it claimed the economic turmoil in the eurozone could not be fixed.
Their intervention came as Nick Clegg told the Guardian the UK would still be "involved" in Europe.
"There will be a lot of opportunities to get back into the saddle. The summit has raised as many question marks as it has provided answers, and there will be a whole lot of discussions about what happens next in which we will be involved."
The deputy prime minister said that the treaty David Cameron vetoed last week was not "unreasonable" but there had been a "breakdown in negotiations".
On Friday Clegg rebuked French prime minister Francois Fillon after his finance minister suggested the UK would suffer a debt downgrade before his country.
Clegg told Fillon that "recent remarks from members of the French government about the UK economy were simply unacceptable” and that steps should be taken “to calm the rhetoric".