A top US military commander has warned about the possibility of civil unrest in Europe, saying the EU brand new deal may fail to hold it together and tackle the escalating tensions over the financial crisis.

"The eurozone is at great risk," Gen Martin Dempsey, who is chairman of the Joint Chiefs of Staff, told an event hosted by the Atlantic Council, a Washington think-tank, as cited by BBC.

"I know that they've taken some measures here with the 17 members of the eurozone to try to better align... monetary and fiscal policy. But it's unclear, to me at least, that that will be the glue that actually holds it together."

Gen Dempsey said a break-up in the European Union could have consequences for the Pentagon - US military has more than 80,000 troops and 20,000 civilian workers in Europe, many based in Germany.

"It will clearly put [budgets] at risk if all the economic predictions about a potential collapse were to occur," Gen Dempsey said.

At an emergency EU summit that ended in Brussels on Friday, the majority of European leaders agreed on a new deal in a bid to tighten fiscal discipline in the eurozone and tackle the bloc's debt problems.

Twenty three states - all seventeen eurozone members and six other EU nations, including Bulgaria - agreed to adopt an accord with penalties for breaking deficit rules.

Four countries including Britain however refused to back a new intergovernmental treaty to deepen the integration of national budgets, raising concerns that the EU may turn into a two-tier system.

Hungary also said it will not play a part in a new inter-governmental agreement, while Sweden and the Czech Republic will consult their parliaments before making a decision.