Nearly 200 illegal immigrants may have died off Libya's western Zuwara coast on Thursday after a boat carrying around 400 people sank, a security official told Xinhua on Friday.

"We have recovered 82 bodies washed ashore so far, while about 100 people are still missing," a coast guard official said.

Libyan coastguards have rescued 201 of the immigrants, while 147 were taken to a detention center for illegal immigrants in the nearby Sabratha town.

The overcrowded boat was found one km off Zuwara coast, a major transit point for immigrants trying to cross to Europe.

The immigrants on board are from Southern Sahara, Pakistan, Morocco, Syria, and Bangladesh, said the official.

Four years after the civil war which toppled former leader Muammar Gaddafi, Libya has descended into anarchy and left a power vacuum in most of its territories, encouraging migrants to venture by sea via the North African country.

It has long been a transit point for migrants seeking to reach Malta, Italy, and other European countries due to its proximity and loose border control.

According to the International Organization for Migration, it is estimated that some 150,000 migrants have reached Europe by sea by mid July in 2015, many of whom departed from Libya.