Jean-Pierre Chevènement, the French interior minister, produced the document for a meeting of EU ministers in Marseille today. Citizens of the EU should be told, the paper says, that Europe will become an area of "cross-fertilisation" ( métissage ).

Diplomats expressed surprise at the blunt language of the text, which avoids any suspicion of Anglo-Saxon political correctness to argue that with declining fertility and birthrates, the issue of legal immigration into the EU must be tackled.

Mr Chevènement, an often outspoken nationalist, created controversy recently when he accused Germany of not having overcome its Nazi past.

"Public opinion must be told clearly that Europe, a land of immigration, will become a place where cross-fertilisation occurs," says the document. Métissage also translates as cross-breeding.

"Public opinion needs to be enlightened and convinced, and more so in countries of recent immigration than others."

But it adds: "To allow access is not to renounce all forms of control. Ensuring cross-fertilisation requires a careful and controlling hand, in immigration terms."

Mr Chevènement is in effect issuing a wake-up call to governments to consider resuming what demographers call "primary migration", encouraging the entry of economic job hunters who intend to stay and bring their families.

But the French minister anticipated that "a reasonable policy of integration" that brought in 50m to 75m immigrants by 2050 would leave unchanged "the percentage of the population of non-European origin".

Jack Straw, Britain's home secretary, is among those attending today's Marseille meeting, organised by France in its role as holder of the EU's rotating presidency. Illegal immigration is one of the topics.

"We need to look imaginatively at how to meet the legal desire for immigration," said a Home Office official in London last night.

But the unvarnished French analysis could fuel anti-EU sentiment in Britain, where the government has pledged to keep border controls and crack down on those it deems false asylum-seekers.

And across the continent, immigration has fuelled anti-foreigner sentiment in a range of countries including Germany, Sweden and Spain. In Austria the issue has been exploited by the far-right Freedom party led by Jörg Haider.

Fears are widespread of a new influx from Poland and Hungary once they join the EU in coming years.

Immigration is an increasing preoccupation for Brussels, but decisions are still made by member states, not the European Commission.

The French document is based partly on a recent survey by the UN Population Division. That said the population of the 15 EU countries and countries currently bidding for membership would fall in the next 50 years from 729m to 628m while the world's population would grow from 6bn to 9bn.

Immigrants, mostly from developing countries, would be needed to fill the vacuum, the UN report argued. Germany recently illustrated one approach to the problem, calling for the immigration of 20,000 IT specialists from India.