Mauritania's former military ruler joined his county's presidential race late Saturday.  Next month's election is part of a power-sharing deal between the country's current military rulers and their political opponents.

Colonel Ely Ould Mohamed Vall announced his candidacy just days after a political power-sharing agreement saw the main opposition parties drop their electoral boycott.

Vall led a ruling military council from 2005 to 2007.  He is the only Mauritanian military ruler to give up power to a civilian president and helped to organize the nation's first free presidential vote, which elected Sidi Ould Cheikh Abdallahi.

Mr. Abdallahi was toppled in a coup last August led by General Mohamed Ould Abdel Aziz.  Aziz then resigned his military commission to run for president in elections that were to be held on Saturday.

But Aziz agreed to delay that vote until July 18 as part of a power-sharing deal in which the opposition will drop its electoral boycott and Mr. Abdallahi will formally resign as president to head a transitional government.

By doing so, Aziz has the opportunity to contest an election more legitimate than the one he would have won Saturday.  But he will also face more challengers in next month's vote - including former military ruler Vall.

In announcing his candidacy, Vall said there is no reason to justify a coup after he handed over power to civilian authorities in 2007.

It was Vall's first public comment on the Aziz coup and sets him on a campaign to challenge Aziz - not only as a civilian candidate, but also as a former military leader with considerable administrative and defense experience, including 20 years as director of national security.

Members of the Aziz campaign say Vall is just another presidential candidate and that his entering the race has no impact on the Aziz candidacy.

Aziz has already been campaigning across the country on a slogan of "constructive change," promising to fight corruption and improve Mauritania's infrastructure.

If no candidate wins an outright majority on July 18, the power-sharing deal calls for a second round of voting on August 1.