A bid by German academics to derail the launch of the European single currency gained ground on Sunday as the country's highest court looked set to admit a legal challenge and 155 professors called for the euro to be delayed.

One of four academics making a legal bid to stop Bonn from joining the single currency said yesterday the Federal Constitutional Court was preparing to admit the case, in a move he said might hold up the euro's launch.

Professor Karl Albrecht Schachtschneider, a law professor leading the so-called "gang of four", said the court had decided to ask the government, parliament, federal states and other bodies to respond to issues raised by the case.

"Bonn will shudder when the request for a statement arrives," Prof Schachtschneider said. "Now Bonn must acknowledge that the constitutional court is taking this seriously."

The court could not be reached for comment. A German government spokesman said he was not aware of any request from the constitutional court.

A letter from the court to Prof Schachtschneider, made available to reporterss and dated February 4th, requested that he provide 25 copies of the 350-page petition which would then be passed on to the bodies for comment.

Prof Schachtschneider said the request was a clear sign the court was about to admit the case.

He said that would make it substantially more likely that the court would grant the academics' request for an injunction stopping Bonn from deciding to join economic and monetary union (EMU) while the main case was being reviewed.

Separately, 155 German and Austrian economics professors, led by Professor Renate Ohr of Hoehenheim University and Professor Manfred Neumann of Bonn, said they would publish a manifesto in newspapers today calling for a postponement of the single currency on the grounds that economic conditions were not right.

Analysts said the news could put talk of a delay back on the agenda just three months before European Union governments are scheduled to choose members of the single currency.