At least 20 people died, most of them women, and another 30 were missing after a boat carrying more than 100 people capsized in a river in central Pakistan on Monday, officials said.

The overloaded boat was heading to a wedding when it capsized in the Indus river in the district of Sadiqabad, the government said in a statement.

Nearly 90 people were rescued by divers, the statement said, adding that the passengers were mostly women and children.

All those on board belonged to one clan, and they were on their way to a family wedding across the river, it said.

"We have retrieved 20 bodies so far" and most of them were women, local government official Aslam Tasleem told local Geo News TV.

He said around 30 additional people were missing.

"We're not sure how many people exactly were on the boat. We're getting the estimates just on the basis of the family members' accounts," he said.

Nearly 35 divers from a state-run rescue service took part in an operation to find and save more people who were in the river, the statement said.

(Writing by Asif Shahzad; Editing by Bernadette Baum)