Violence reached even Afghanistan's political elite when a former president was killed by a suicide bomber [Reuters]

A pair of suicide bombers have struck in Afghanistan's main southern city Kandahar, killing three people, officials said.

Assadullah Khalid, minister of border and tribal affairs and chief security co-ordinator for the south of the country, said he believed he was the target of the first attack which left two people dead.

But Afghanistan's interior ministry said there was no evidence the blast was aimed at Khalid.

"There was an explosion - a suicide bomber wearing explosives on his body detonated in an area where there was not an obvious target," an interior ministry spokesman told AFP.

Shortly afterwards in a different part of the city, a suicide bomber wearing an army uniform struck inside an army garrison.

"It was a suicide attack that killed one guard, the attacker as well as wounding two army soldiers," said General Abdul Hamid, commander of the army unit whose garrison was struck.

It is relatively easy to buy army uniforms from Afghan markets and there have been a string of attacks this year committed by attackers wearing them.