* Losing candidates claim result falsified
* Court has power to invalidate Abdel Aziz win * Observers, diplomats say vote was fair
(Adds comment from French parliamentary delegation)
By Vincent Fertey
NOUAKCHOTT, July 22 Mauritania's defeated presidential candidates have appealed against the victory of junta leader Mohamed Ould Abdel Aziz in a weekend vote, but election observers said there were no grounds for a challenge.
Abdel Aziz, who last August overthrew the country's first democratically elected leader in a coup that brought widespread international criticism, took 52.6 percent of the vote, according to the interior minister.
The election was intended to show donors and investors that Mauritania was ready to the rejoin the international community from which it has been marginalised since the putsch, but three prominent candidates want it annulled.
"We have lodged an appeal with the constitutional court to protest against the manner in which the presidential election was conducted," Ahmed Ould Daddah, one of the unsuccessful candidates, told a news conference late on Tuesday.
"Our arguments show clearly that this election has been falsified," he said.
With him, fellow losers Ely Ould Mohamed Vall and Messaoud Ould Boulkheir denounced the vote as an "electoral masquerade".
The court, which can take eight days to examine the appeal, has the power to declare the result invalid, but signs from international observers and diplomats posted to the desert state indicate that Sunday's result will be accepted.
"In everything we have seen, we judge quite simply that these elections took place in an orderly and transparent fashion," African Union envoy Mohamed Saleh Annadif said.
A delegation of French parliamentarians who observed voting issued a statement saying the elections could be considered "honest and regular".
NO MORE CRISES
The challengers says observers were too few in number and too inexperienced in Mauritanian politics to accurately judge the transparency or otherwise of the poll, but diplomats disagree.
"Everything supports the belief that the elections have been organised transparently, multiparty, and without major incident," said a Western diplomat in Nouakchott.
After almost a year of international criticism, and given the tortuous route to elections, which involved boycott, delay and mediation, it may be that there is little appetite for further wrangling.
"Mauritania is coming out of its crisis, and on that basis it's likely that the international community will restart cooperating with Mauritania," the diplomat said.
So far, key aid donors such as the European Union, which suspended a 156 million euros ($221.6 million) aid programme in response to the 2008 putsch, have not commented on the election.
Neither Vall nor Daddah, despite being considered among the more influential Mauritanian politicians, were particularly vociferous critics of Abdel Aziz or his putsch, leaving Mohamed Ould Maouloud to act as mouthpiece for anti-junta coalition the National Front for the Defence of Democracy (FNDD).
They should now allow the country to drag itself back towards international acceptance, some Mauritanians say.
"They have to be good losers and recognise the result of the election. Mauritania must not be allowed to fall into another political crisis," said businessman Mohamed El Mamoune Dide. (Additional reporting by James Mackenzie in Paris; Writing by Daniel Magnowski; Editing by Jon Boyle)