The army seized power on Wednesday, while President Maaouya Ould Sid'Ahmed Taya was out of the country, and installed what it called the Military Council for Justice and Democracy which has vowed to hold presidential polls within two years - and promised none of its members will stand.
Thousands of people clad in traditional blue and gold boubous marched through the sandy streets of Rosso, a frontier town on the Senegalese border, late on Saturday after the military outlined its plans for the West African country.
"Mauritanians had lost all hope of development, democracy and social justice. But this is our moment," said Ahmed Diop Moctar Neche, a pharmacist shouting to be heard above the crowd.
"This is not the Mauritania of yesterday. They cannot tell lies to the people," he said.
One man held a picture of Colonel Ely Ould Mohamed Vall, the military government's leader, above his head in the middle of the throng.
Police officers and soldiers were among the crowd.
"We felt trapped, condemned, like a prisoner who had lost all hope of being freed," said Baba Ould Soufi, 48, an agricultural engineer.
Past coup bids
Taya seized power in a 1984 coup and ruled with an iron fist for two decades.
Dissident soldiers nearly toppled him in 2003 and the government says it foiled two more coup bids in 2004.
Maaouya Ould Sid'Ahmed Taya
ruled with an iron first for 20 years
Thousands of black Africans - who make up about one-third of the population in a country where light-skinned Moors have long dominated government - were forcibly expelled from the region around Rosso during Taya's rule.
"We are listening. If the new rulers do something that is in our interest we may go back," said the elderly head of a community of refugees in Dagana, a village close to Rosso on the Senegalese side of the border.
The United States, former colonial power France and the United Nations have all condemned the putsch. The 53-nation African Union (AU) has suspended Mauritania.
But Mohamed Abdellahi Ould Babana, Mauritania's ambassador to Ethiopia who sits on the AU's human rights commission, said he believed the AU suspension would not last long.
Junta leader Ely Ould Mohamed
Vall promises to hold a plebiscite
"It's a provisional suspension. If they came here, they would see how people have received the new regime. The AU will come back to its senses and see the will of the people," he said.
The self-styled military government promised on Saturday to hold a referendum on changes to the constitution within a year to be followed immediately by legislative elections.
It has met members of the Islamic Republic's opposition parties, Taya's own party, business leaders and diplomats based in the capital Nouakchott.
A judge freed 21 people jailed since 25 April on charges of plotting against the state, said Captain Ahmed Ould Abeid, head of the central prison in the capital. The group has yet to be acquitted of charges.
They included Mohamed Hassan Ould Dedew, spiritual leader of many Mauritanians the government brands as Islamic radicals, and Moktar Ould Mohamed Moussa, an Islamic leader who previously served as ambassador to the United Arab Emirates.
At least 50 other people remain in prison on similar charges. Taya jailed scores of opponents during his rule, including politicians, soldiers and Islamists he portrayed as terrorists plotting his overthrow.
Older Mauritanians find the promises familiar - a military committee staged a bloodless coup in 1978 pledging democracy only for another putsch to overthrow it two years later.
But many hope this time it will be different.
"The dictator's time has come to an end"
El Hacen Soumailim,
The prospect of oil wealth when the country starts pumping crude early next year, and people's pent-up anger at years of misrule and corruption, mean more is at stake than ever before, they say.
"The dictator's time has come to an end," said El Hacen Soumailim, a student in Rosso.
"My support for the military council is almost total, but their promises have to be wholly respected in the next two years. We've had enough of heads of state who stay on for decades."