British Prime Minister David Cameron says the Catalonia region of Spain would be forced to leave the European Union if separatists manage to pull off a secession drive and carve out a new Mediterranean nation.

Speaking in Madrid Friday, Cameron said, "if one part of a state secedes from that state it's no longer part of the European Union and it has to take its place at the back of the queue, behind those other countries applying to become members of the European Union."

Catalonia has regional parliamentary elections Sept. 27.

Separatists hope voters will elect lawmakers committed to setting Catalonia on a path toward a unilateral independence declaration. Many insist an independent Catalonia will remain in the EU.

Spanish Prime Minister Mariano Rajoy says secession for Catalonia is unconstitutional.