Malian Prime Minister Cheick Modibo Diarra quit Tuesday under pressure from former putschists opposed to a regional military intervention against Islamists controlling the north, a move that drew international condemnation.

The troubled west African nation's interim president, Dioncounda Traore, swiftly appointed Django Sissoko to replace Diarra and promised a new government by the end of the week.

The UN Security Council condemned the arrest of Diarra by soldiers on orders from former coup leader Captain Amadou Sanogo, which was followed several hours later by his resignation in what one analyst dubbed a "quasi-coup".

The council joined calls from France, the United States, the European Union and the regional bloc ECOWAS for the military to stop meddling in political affairs, and threatened targeted sanctions against those preventing the "restoration of constitutional order."

US State Department spokeswoman Victoria Nuland called the move against Diarra, a US citizen, "a setback for Mali's transition."

The fresh crisis comes amid mounting confusion over plans for a foreign military intervention to drive out Islamists who occupied over half of Mali's territory in the wake of a coup led by Sanogo in March.

UN spokesman Martin Nesirky said Secretary-General Ban Ki-moon was "troubled by what happened in Mali."

Diarra's resignation came a day after the EU approved plans to deploy an military training mission of some 250 troops Mali to help the government regain control of the vast semi-desert north.

The 60-year-old astrophysicist and former chairman of Microsoft Africa was seized at home by soldiers late Monday and hours later at dawn went on state television to announce he was stepping down.

"I, Cheick Modibo Diarra, resign with my government," he said solemnly.

A spokesman for Sanogo's former junta in Europe, Bakary Mariko, told France 24 television the sequence of events was "not a new coup d'etat" but observers say it was clear he was strongarmed.

"The latest episode of the Malian crisis looks like a quasi-coup carried out by the former -- but still influential -- military junta and its allies," said London-based analyst Samir Gadio.

"The objective is most likely to prevent a direct ECOWAS military deployment in Mali which would undermine the power base of Captain Sanogo and his associates."

A member of Diarra's family, speaking on condition of anonymity, told AFP the former premier was "under house arrest. There are soldiers at his house and he is not free to move around."

French foreign ministry spokesman Philippe Lalliot and EU foreign policy head Catherine Ashton called on Mali to appoint a new prime minister acceptable to all sides, while ECOWAS stressed the need for an "inclusive, representative government."

The interim president answered foreign concerns by swiftly naming Django Sissoko, until now Mali's ombudsman, as the new prime minister and promising to give the country a new government by the end of the week,

Diarra was a staunch advocate of French-backed plans to send in a west African intervention force to drive out the extremists, who are running the zone according to their brutal interpretation of sharia Islamic law.

Citizens have been flogged, had their hands amputated and been stoned to death as punishments for transgressions.

Such foreign intervention is fiercely opposed by Sanogo, who still wields considerable influence in Bamako despite handing over power to an interim government after his March 22 coup.

Sanogo's coup was sparked by soldiers' anger over their rout at the hands of well-armed Tuareg separatist rebels seeking independence for their homeland in the north.

While he handed over power to a civilian government, Sanogo continued to wield significant influence, and interim authorities remained paralysed as the Tuareg, allied with Islamists, continued their juggernaut, seizing the northern triangle of the bow-tie shaped nation, an area larger than France.

Divisions between the Islamists and secular Tuareg over the future of the occupied are saw the alliance crumbled and the Al Qaeda-linked extremists forced the Tuareg out of their positions by June.

Europe, the United States as well as Mali's neighbours fear the vast zone will become a haven for terrorist groups and pose a threat to their countries.

West African nations are pressing hard for the United Nations Security Council to approve the foreign force and Germany and the United States have also offered training and logistical support.

But misgivings are rife over the plan to send in 3,300 west African troops. Many of Mali's neighbours still prefer a negotiated solution and both the UN and US have urged caution and demanded more detail on the force's capabilities.

"Everything has fallen apart," an African diplomat based in Mali told AFP. "It is starting to appear as if the Americans are right, the problem in Bamako must be solved first."

Deep divisions in Malian society led to a second postponement of planned national talks due to start Tuesday to plan the transition back to democracy and tackling the security crisis in the Islamist-occupied north.