The death toll from a bomb that ripped through a hospital in southwest Pakistan on Monday has risen to 40, a provincial minister told AFP.

"The last information we had was 40 dead but it may increase," said Saleh Baloch, health minister for Balochistan province, after the blast in the provincial capital Quetta. 

"There were around 40 people injured when we were shifting them to hospitals. But now mobile jammers have been activated and so we don't have updated information."