Pakistani officials say a roadside bomb has gone off near a vehicle escorting a judge in the country's southwest and 10 people were wounded.

Sarfraz Bugti, the head of the interior ministry in southwestern Baluchistan province, says the judge was unharmed in Thursday's explosion, which took place on a main road in the city of Quetta.

Police spokesman Shahzada Farhat says police officers and passers-by were wounded.

No one immediately claimed responsibility for the bombing, which comes just four days after a suicide bomber struck a hospital in Quetta, killing 70 people, mostly lawyers.

That attack took place shortly after a prominent lawyer was gunned down earlier in the day and his body was brought to the hospital.

Quetta is the capital of Baluchistan province.