European media Monday raised serious concern over the low voter turnout which undermined an otherwise strong Spanish vote in favour of the adoption of the EU constitution.

The 42 percent Spanish voter participation rate in the Sunday referendum was seen by many European newspapers as a warning to the "yes" camp in the nine other EU countries going to the polls on the EU constitution.

The Spanish left-wing daily El Pais said the "lack of uncertainty about the result" had kept voters away. However the low turnout was a signal to other governments to work harder to mobile the "yes" vote, it said.

The right-wing Razon said Spain had said yes "without enthusiasm" and that the other nations planning polls needed to take the low voter participation into account.

That theme was repeated in France, which could hold its referendum as early as May, with the regional Dauphin Libere saying the French "yes" camp needed to work harder to get voters involved and to develop clear and convincing arguments.

The conservative French daily Le Figaro described the yes vote at 77 percent vote as being "without ambiguity" but "disappointing" due to the low level of voter turnout at 42 percent.

Joining France in popular votes on the referendum are those with strong euroskeptic camps like Britain, Poland and the Czech Republic.

In Britain, which will hold a referendum early next year, the left-wing daily The Guardian said the EU constitution had pasted its first hurdle in a "quiet yes vote" which will disappoint European leaders.

However it said other national votes were far from certain as Spain was seen as being enthusiastic about Europe, which helped consolidate its democracy after the death of military dictator General Francisco Franco in 1975. Other countries holding referendums "are less keen - and not only in chronically semi-detached Britain."

The Financial Times in a front page article said the low turnout would send "worrying signals " to the other nine EU countries putting the constitution to the vote.

While in the Netherlands and Poland, which face popular consultations later this year, the press also expressed disappointment and concern at the low voter turnout.

"It would be difficult to consider these results as encouraging," said the left-wing Polish daily Rzeczpospolita. It added that if the participation rate is less than 50 percent in Poland -- one of 10 new EU members -- then the result does not count and the decision is transferred to the parliament.

The Dutch right-wing daily Le Telegraaf and the left leaning Protestant daily Trouw both expressed concern about the low voter turnout.

Denmark, Ireland, Luxembourg and Portugal are also planning referendums.

The remaining 15 member states of the EU bloc, including the largest nation, Germany, have preferred parliamentary ratification.

The right-wing daily Die Welt said the low participation rate showed that "for the moment the public debate about the European constitution hasn't really started yet." The 480 page document "remains largely unknown by the European public, it said.

The German centre-left daily Sueddeutsche Zeitung said that Spanish Prime Minister Jose Luis Rodriguez Zapatero had not convinced the masses about the EU constitution as demonstrated by the low participation rate, the lowest since the restoration of democracy in 1975.

Beyond Germany, parliaments of Slovenia, Lithuania and Hungary have already ratified the text, as has the lower house of the Italian parliament, though the Italian upper chamber still has to approve the text.

The Italian media were largely positive about the Spanish vote with the centre-left La Republica saying Zapatero had "won the prize for Europeanism" and main daily Corriere della Sera saying the Spanish Prime Minister had "won the referendum challenge".