KANDAHAR: A pair of suicide bombers struck outside the airport in Afghanistan's southern city of Kandahar on Wednesday, killing 20 civilians and wounding 50, officials said, in one of the most bloodiest attacks in recent weeks.

Four provincial governors from the south were at a meeting at the sprawling Nato base at the airport when the attack took place, General Abdul Hameed, Afghan army commander for the southern region, told Reuters.

A bomber on a motorcycle blew himself up in a parking lot near the base packed with truck drivers and other civilians waiting to get into the facility.

A few minutes later, as people gathered at the site of the blast, another bomber on foot walked into the crowd and detonated his explosives, said Ahmad Faisal, a spokesman for the provincial governor.

A spokesman for the Nato-led force said the coalition was aware of the incident, but directed all questions to civilian authorities.

Violence has surged across Afghanistan since the Taliban began a spring offensive in April, vowing to target the Afghan government and security forces, as well as the 130,000 foreign troops in the country.

Kandahar, the so-called birthplace of the Taliban, has seen some of the worst attacks.

The violence has stoked concern that Afghan forces may struggle against a Taliban insurgency at its deadliest once most Western combat troops leave by the end of 2014.

Foreign forces are still leading security in Kandahar province, but the capital city of Kandahar is meant to go into Afghan control in the current phase of transition.