British Prime Minister David Cameron has warned against calls by some eurosceptics for Britain to adopt a Norwegian model for relations with the European Union.

He made the statement as debate is heating up ahead of a membership referendum.

"Norway actually pays as much per head to the EU as we do, they actually take twice as many, per head, migrants as we do in this country, but of course they have no seat at the table, no ability to negotiate," he told parliament.

Norway is not a member of the EU but is part of the European Economic Area, which includes Iceland, Liechtenstein and Switzerland.

Some eurosceptics want Britain to leave the EU and negotiate similar economic agreements with the bloc.

Cameron has promised to hold a referendum on EU membership before the end of 2017 and has said he will campaign to stay if he can obtain reforms that would loosen Britain's ties with the rest of the European Union.

He has not yet ruled out supporting "Brexit" if he cannot. Now Cameron is increasingly under pressure to clarify his own position as the pro and anti campaigns rev up.