The bomb went off mid-afternoon not far from an International Security Assistance Force base, an ISAF spokesman in Kandahar told AFP.
"Two ISAF soldiers have been wounded," Squadron Leader Jason Chalk said.
He would not give the nationalities of the soldiers involved. The 37-nation ISAF leaves such announcements to the home nations of the soldiers involved.
There are 2,300 Canadians in Kandahar province but a spokesman for the Canadian deployment said its forces were not involved.
Chalk said there were no details of civilian casualties. Police only reported that the foreign soldiers had been hurt.
The soldiers were evacuated from the scene of the blast, on a road between the city and its airport, by helicopter, an AFP reporter at the site said.
Police said the explosives had been packed into a minibus that was detonated as the convoy passed. An ISAF vehicle was damaged.
The road was blocked off and a large crowd had gathered at the site.
Suicide attacks blamed mostly on rebels linked to the extremist Taliban movement have soared this year, with Kandahar seeing most of the attacks.
However there had been a drop-off in suicide bombings in the last few weeks. The last in Kandahar city was on October 13, Chalk said.

Copyright AFP (Agence France-Presse), 2006