The new European Union treaty will mean "transfers of sovereignty" from Britain and Gordon Brown is right to hide the fact from the public, an EU leader admitted yesterday.
Jean-Claude Juncker, Luxembourg's premier and leader of the bloc of 13 single currency members, spoke out as the Prime Minister faced rising calls for a referendum on the treaty drawn up following the rejection of the old EU constitution by French and Dutch voters in 2005.
Mr Juncker said he supported public debate on the treaty - except in Britain.
"I am astonished at those who are afraid of the people: one can always explain that what is in the interest of Europe is in the interests of our countries," he told Belgian newspaper Le Soir.
"Britain is different. Of course there will be transfers of sovereignty. But would I be intelligent to draw the attention of public opinion to this fact?"
Mr Juncker, a supporter of a United States of Europe, described the June 23 deal signed by Tony Blair as an "objective success" for friends of the EU constitution.
"There is a single legal personality for the EU, the primacy of European law, a new architecture for foreign and security policy, there is an enormous extension in the fields of the EU's powers, there is Charter of Fundamental Rights," he said, listing elements of the old constitution in the proposed treaty.
His remarks come as a further blow to Mr Brown as pro-referendum campaigners vowed to target Labour MPs in marginal constituencies.
The Open Europe campaign and other pro-referendum groups aim to put maximum pressure on MPs before a likely Commons vote next year on ratifying the treaty.
As with Mr Blair before him, Mr Brown has insisted that Britain's negotiating "red lines" were not broken at last month's summit - and therefore no referendum is needed.
But Mr Brown has hinted at some flexibility by saying he is prepared to listen to the national debate.
In its manifesto for the 2005 general election Labour promised to hold a referendum on the old constitution. The "no" results in France and Holland spared Mr Blair from having to deliver on that promise.
Last night, Open Europe served notice that anti-referendum MPs from all the main parties would face sustained pressure in their own constituencies in the coming months.
Lord Leach of Fairford, the Tory peer who is chairman of Open Europe, told The Daily Telegraph: "Gordon Brown should think twice before going back on his party's manifesto pledge to hold a referendum on a treaty that is the EU constitution in all but name.
"If he is serious about wanting to 'listen and learn' he should let the people have a say. We are building a formidable coalition to ensure that the Government keeps its promise."
An ICM/Open Europe poll recently found that 86 per cent of voters want a referendum on the treaty while 43 per cent of Labour supporters would be "definitely less likely" to vote for Mr Brown if he refuses one.