At least 40 migrants, including children, have died after their boat sank off the coast of Tunisia, in one of the deadliest maritime disasters in the region this year, authorities say. 

The boat sank off the Mediterranean port of Mahdia in central Tunisia while carrying about 70 migrants, an official said. 

All the people on board were from sub-Saharan Africa, the official added, without providing further details.

This is the latest disaster to hit migrants trying to cross the Mediterranean from Africa to Europe.

Over 210,000 people tried to cross the Central Mediterranean in 2023, according to data shared by the UN. 

More than 60,000 were intercepted and sent back to African shores, while nearly 2,000 lost their lives at sea.

About 30 migrants were rescued in the latest disaster which occurred on Wednesday. 

Tunisian authorities have opened an investigation into the causes and circumstances surrounding the boat's sinking.

The country is facing growing pressure to manage migrants fleeing conflict and poverty in search of better opportunities in Europe.

The sea migration route between Africa and Europe is one of the most dangerous in the world. 

Last February, a boat sank off the Tunisian city of Sfax with more than 40 Sudanese people on board. 

In 2023, the European Union (EU) signed a deal with Tunisia to tackle irregular migration.

The deal includes $118m (£90m) to stop smuggling, strengthen borders and return migrants.