Workers carrying out do-it-yourself pest control have caused an explosion at a Melbourne restaurant.

Ten cockroach bombs were set off inside the Le Bangkok Thai restaurant on Lonsdale Street in the CBD just before 1:00am (AEST).

It caused an explosion that blew out a door, damaged a wall and shattered a second storey window.

One of the workers suffered cuts to his arm and was treated by paramedics.

Building and health inspectors will examine the building on Monday.