Diamond exports from Sierra Leone saw a steep fall in 2015, the deputy minister for mines said Wednesday, with miners restricted from working while the Ebola virus ravaged the country.

The Deputy Minister of Mines and Mineral Resources, Abdul Ignost Koroma, told journalists "diamond exports in 2015 were 500,039 carats compared to 620,181 carats in 2014," down 20 percent.

The fall in value of the exports was even greater, from $221 million to $154 million year-on-year, he said, a drop of 30 percent.

While the primary cost of the 2014-15 Ebola outbreak was in human lives, the crisis also wiped out development gains in Sierra Leone, which was devastated by 11 years of civil war ending in 2002.

The 18-month crisis severely affected the key diamond mining sector as health regulations to combat the spread of the disease restricted miners from going into the fields.

Ebola slashed growth to four percent in 2014 and the economy contracted by a massive 21.5 percent in 2015, according to official figures.

Sierra Leone is the leading diamond producer and exporter in west Africa. The third-largest diamond in the world, the near-1000 carat "Star of Sierra Leone", was discovered there in 1972.