Colonel Samba Diallo, Guinea-Bissau's former deputy head of military intelligence, was shot by men wearing uniforms while seated at the terrace of a restaurant near his home in Bissau.

The identity of the attackers is not yet known and no clear motive has emerged.

Diallo had served under ex-Army Chief of Staff, Jose Zamora Induta, until the two were deposed and jailed in a mutiny in April 2010. Diallo was released after 8 months and since then had held no official responsibilities in the army.

He was accused of involvement in a bombing in 2009 that killed the country's then army chief, Batista Tagme Na Waie, and prompted the murder of President Joao Bernardo Vieira.

Western diplomats have said the 2010 mutiny was probably over control of the lucrative illegal drugs trade. Guinea-Bissau is reputed to be the main African transit point for South American cocaine bound for Europe.

An estimated 1000 kilograms of the drug are flown into Guinea-Bissau every night, according to a leaked 2009 US diplomatic cable.

Leading candidates in Sunday's election have promised to make fighting drugs a priority.

Results expected within a week

The favourite to win the poll is former prime minister and ruling party candidate, Carlos Gomes Junior. He is up against Manuel Sherifo Nhamadjo, who dropped out of the ruling party to run as an independent, and Kumba Yala, an ex-president who shares the Balanta ethnicity with a quarter of the population and most of the army.

Gomes Junior's rivals have accused him of fomenting instability and tolerating drug-running during his time as premier, which saw multiple assassinations including the killing of President Bernardo Vieira in 2009. Gomes Junior denies the allegations.

Election observers said the voting appeared to pass off peacefully in the country of 1.6 million people and that counting was well underway. The results are expected within a week and if no candidate wins an outright majority, a run-off will be held, probably in April.

Concerns about violence

Sunday's election came after the last president, Malam Bacai Sanha, died in January following a long illness. Although the three-week election campaign was peaceful, some fear violence or even another military intervention if the army does not approve of the winning candidate. "There is a lot of concern and apprehension," political anaylst Rus Landim told AFP. "If everything is handled peacefully we can save the stability, but for now there is a risk that things can degenerate."

Guinea-Bissau's vote will be seen as another test for democracy in a region that has recently seen a flurry of troubled elections. Polls in the Ivory Coast in 2010 sparked a civil war. In Senegal, where a run-off is due on March 25, there has been deadly street violence.

Author: Mark Caldwell (AFP, Reuters)
Editor: Sarah Steffen / rm