There are fears the plan could lead to a brain drain from poorer nations

The plan would allow suitably qualified people and their families to live and work within the European Union.

The EU says it needs 20m skilled workers over the next two decades, and is very short of expertise in engineering and computer technology.

The scheme, which is more restrictive than the US Green Card, would need the approval of all 27 EU member states.

Correspondents say another aim of the plan is to reverse a current trend under which skilled migrants, mostly from Asia and Africa, emigrate to the US to find work.

'Centralisation too far'

The BBC's Mark Mardell in Brussels says the proposal is controversial and some countries are sure to oppose it.

Critics also fear that Europe's attempt to take the best and leave the rest will only encourage a brain-drain from poorer nations.

The UK, Ireland and Denmark could opt out, but the other EU members will have to take part.

UK ministers say they are studying it, but our correspondent says they are not keen on the card, preferring to develop an Australian-style points system.

Unveiled at the European Parliament in Strasbourg on Tuesday afternoon, the Blue Card would enable holders and their families to live, work and travel within the EU.

To be eligible, new immigrants would need to show a recognised diploma and have at least three years professional experience.

They would also need the offer of a job, for a minimum one-year contract, which could not be filled by an EU citizen.

European Justice Commissioner Franco Frattini said: "This is not an 'open doors' policy."

"If a given member-state needs engineers or doctors, it has to decide how many, and then I will provide a state with a common procedure," he added.

But some politicians in the Netherlands and Germany are hostile and the Austrian government has condemned the plan as "a centralisation too far".

Across Europe there is a real tension between politicians, who know voters are worried about immigration, and businesses demanding graduates from India and China, our correspondent says.