Mark Doyle in Niamey: "Long struggle ahead for civilian politicians"

The prime minister, Ibrahim Assana Mayaki, said the military would remain in power until the formation of "a government of national unity" in a few days.

Some reports said military officers had been meeting to name a new head of state.

MPs have condemned the prime minister's move to dissolve parliament. They said they would continue to operate.

They said that the constitution says the parliamentary speaker takes power and organises elections following the death of the head of state. Some brandished copies of the document.

David Brown: "Long-term stability is still some way off"

BBC West Africa Correspondent Mark Doyle says the country is now suffering from a power vacuum.

The assassinated military leader did organise a series of elections during his period in power, but the results have been consistently rejected by pro-democracy activists as rigged.

French news agency AFP said that two possible successors have been mentioned - Major Daouda Mallam Wanke, who commands the first military region and the presidential guard, and Colonel Moussa Moumouni Djermakoye, the army chief of staff.

It reported Togolese sources as saying that Major Wanke had been directly involved in the assassination and had been slightly wounded.

State radio has announced that President Mainassara will be buried on Sunday.

Borders reopen

Ordinary people have been trying to go about their normal lives. State controlled radio has reported that the borders have reopened and most of the troops deployed in the capital Niamey on Friday withdrawn.

The colourful central market has reopened and trade is picking up again. Niamey is built alongside the River Niger and is a key trading centre for this part of the Sahara.

Confusion over killing

President Mainassara: Took power in a coup in 1996

Details of the president's assassination remain sketchy.

American diplomats said he was killed at Niamey airport by members of his personal guard after trying to sack his chief of military staff, Musa Mumuni Djermoukoi.

Reports said the president was shot as he prepared to board his helicopter on a trip to a provincial town.

The prime minister described the president's death as "an unfortunate accident".

Correspondents have said the assassination events bore all the hallmarks of a coup d'etat.

Martial music played on Niger radio

The killing means more uncertainty for the people of Niger. The country has been under a military regime since General Mainassara seized power in a coup d'etat three years ago.

Condemnation

Niger's giant neighbour, Nigeria, has expressed concern about the possible impact of the killing. It had built up good relations with the former president.

The head of the regional trade body Ecowas has also condemned it, saying it deplored all attempts to take power by force.

UN chief Kofi Annan has appealed for a return to constitutional order.

A statement said the secretary-general called on all "political, military and civil society leaders to make every effort to avert violence in the country".

The leader of neighbouring Libya, Colonel Muammar Gaddafi, also expressed his concern.