A bomb at a hospital in Pakistan's southwestern city of Quetta on Monday killed 45 people and wounded more than 50, the provincial health minister said, significantly raising the casualty toll from initial estimates.

"There are many wounded, so the death toll could rise," said Rehmat Saleh Baloch, health minister for Baluchistan province.

The bomb exploded as mourners, mostly lawyers and journalists, gathered to accompany the body a prominent lawyer who was shot and killed in the frontier city earlier on Monday.