Authorities say four civilians have been killed in a car bombing outside a bank in a major southern Afghan city.

The bomb went off as soldiers and police officers were lined up to collect their salaries at the bank in Lashkar Gah, the capital of Helmand province.

More than 20 people were wounded in the blast, including 10 soldiers and six police officers.

No one immediately claimed responsibility for the attack.

Less than three hours later, two explosions hit the south's largest city - Kandahar.

The first blast in Kandahar was a car bomb outside the city's main hospital that wounded seven people. A suicide car bomber blew up his vehicle near a police compound in the city, wounding 16 people.

Bombings by insurgents are a regular occurrence in volatile southern Afghanistan.