NOUAKCHOTT  - Mauritanian police on Thursday broke up a protest by hundreds of people against an army coup in the West African nation which has been internationally condemned despite a junta promise to hold new elections. The European Union called for the release of President Sidi Ould Cheikh Abdallahi, the country's first democratically elected leader, and his Prime Minister who were detained after the army takeover on Wednesday. The Arab League and African Union each expressed concern and sent missions to Nouakchott, where a top official in Abdallahi's party said police fired tear-gas to end the rally in support of the president. "We wanted to organise a peaceful demonstration, our protesters were only armed with slogans and portraits of the President. The police stopped us by firing tear-gas," party Secretary-General Muhammad Mahmoud Ould Dahmane said. One woman was injured during the protest in the capital, he added. Earlier, around 1,000 people also marched through the capital in support of coup leader General Muhammad Ould Abdel Aziz, who seized control hours after being sacked as head of the presidential guard. Pro-coup demonstrators marched alongside vehicles bearing giant portraits of the general and chanted "Aziz, Aziz" as they marched to the presidential palace. Addressing the crowd at a rally outside the Presidential Palace at the end of the march, Abdel Aziz promised to solve country's problems in his first public speech since taking control. "I will work to solve all the problems this country is confronted with," said the General, who was flanked by members of the ruling junta. Police in riot gear were deployed at strategic junctions around the capital. But the junta promised to quickly hold new elections as it confronted international condemnation of Aballahi's detention. The junta said in a statement it would "supervise the holding of presidential elections enabling the relaunch of the democratic process in the country and to reshape it on a perennial basis." It promised: "These elections, which will be held in the shortest possible period, will be free and transparent and will bring for the future a continued and harmonious functioning of all the constitutional powers." Abdallahi remained in custody Thursday at the headquarters of the Presidential guard, according to a security source. The Prime Minister, former interior minister and two other officials considered close to Abdallahi were also arrested, security sources said. The coup triggered international condemnation, with the United States urging the release of Mauritania's leaders and the EU threatening to cut off aid. The European Commission said the President and Prime Minister must be released by the junta before any fresh elections. "The current situation is unacceptable. A military coup of this nature is unacceptable against a democratically elected president," commission spokesman John Clancy told reporters in Brussels. UN Secretary-General Ban Ki-moon called for "the restoration of constitutional order." The African Union called for maintaining "constitutional legality" and said its peace and security commissioner, Ramtane Lamamra, would go to Mauritania to "assist in promoting a peaceful solution to the crisis." An Arab League delegation was also to go to Mauritania on Friday. The largely desert country has a history of coups since gaining independence from France in 1960, and on the morning after the coup, Mauritanian newspapers echoed a sense of deja-vu. "Coup d'etat: how did we get back to the starting point?" asked the Le Quotidien de Nouakchott daily. The Biladi newspaper spoke of "Democracy tested" while Nouakchott Info headlined: "Coup d'etat, the end of an era".