Former parliament speaker Dioncounda Traore took over as Mali's interim president on Thursday from the leaders of last month's coup, promising to hold elections and fight rebels occupying half the country.
Traore, 70, a labour activist turned politician, was sworn in by Supreme Court President Nouhoum Tapily in the capital Bamako as part of a deal to restore civilian rule after army officers staged a March 22 coup in the West African state.
The coup shattered predominantly Muslim Mali's image as one of the most peaceful and stable states in the region.
Triggered by army anger over the previous civilian government's failure to tackle a Tuareg-led rebellion in the north, it backfired spectacularly, allowing the rebels to advance and declare a northern separatist homeland. Al Qaeda-linked Islamist fighters are among the occupying rebels.
With residents and UN rights experts reporting killings, rapes and looting on the rise in rebel-seized northern towns, there are fears of the vast northern territory becoming a lawless and destabilising "rogue state" in West Africa.
"We will never negotiate the partition of Mali," Traore said in his inauguration speech in which he promised to organise "free and transparent elections" over the whole of the national territory.
Former President Amadou Toumani Toure, deposed by last month's coup, resigned to facilitate the transition deal.
"I am president of a country that loves peace," Traore said, wearing the presidential sash over a dark suit. But he acknowledged he was the leader of a nation "cut in two". He called on the rebels to pull back from the northern towns they occupied, which include the desert trading post and seat of Islamic learning Timbuktu and the garrison town of Gao.
"We prefer peace, but if war is the only way out, we will wage it," Traore said. "Long live Mali, one and indivisible!"
He said the effort to recover Mali's territorial integrity would expel "invaders bringing desolation and misery" which he identified as al Qaeda, drug-traffickers and hostage-takers.
But there were no immediate signs that Mali's army, weakened by the putsch, was readying any significant offensive against the rebels, whose ranks were swelled by arms and Tuareg soldiers who had served slain Libyan leader Muammar Gaddafi.
The 15-state ECOWAS grouping of West African countries, which pressured the Bamako coup leaders to give up power, is preparing an intervention force of up to 3,000 troops. But it has said its mandate is to prevent further rebel advances rather than win back lost territory. Former colonial power France has offered logistical support but not troops.
In Geneva, UN Secretary-General Ban Ki-moon welcomed what he called the "constitutional restoration" in Mali and said he was discussing with West African leaders how to deal with the rebel-occupied north.
"We sincerely hope this will be resolved as quickly as possible so that the Malian people will really enjoy their genuine feedom and stability and also development," he said.
Malians seemed relieved to have a president in charge again. "He has to show what he is capable of," said Bamako resident Youssouf Ndiaye.
Traore is not expected to have enough time to organise credible elections in the 40 days alotted to him by the constitution.
Tiebile Drame, head of PARENA, one of the Malian political parties that led opposition to the coup, said talks between Malian political actors were expected in Burkina Faso over the weekend. It was hoped this could lead to the naming of a prime minister over the weekend and a government next week.
But Drame saw little prospect of quick progress on the military front against the rebels. "Everybody knows it is not possible to conduct a war in 40 days, especially with the state of our army," he said. "We are a collapsed state."
UN human rights chief Navi Pillay condemned reported violations being committed against civilians after the coup and rebel advance. She said the situation risked worsening a grave humanitarian crisis already affecting the drought-plagued Sahel region, now awash with refugees.