MAASTRICHT, Netherlands (AP) — The European Union's Commission chief has used the 25th anniversary of the summit to reinforce the goal of an ever-closer union to lambast some member states that refuse to apply common rules and said the bloc needs to rethink a looser relation for those not fully committed to the common cause.

Jean-Claude Juncker acknowledged a quarter century after the Maastricht Treaty on tightly knit unity that Britain and others had changed conditions to the extent that he was considering a system where some, beyond a primary group of nations, would be in "a different orbit" to remain linked up but not necessarily close.

The 28-nation EU has been rocked by the British exit referendum last year, and acrimonious relations with some eastern members on migration and constitutional law.