Riyadh (AFP) - Saudi Arabia has stopped granting visas to workers from Guinea, Liberia and Sierra Leone, the countries worst-hit by the deadly Ebola virus, the labour ministry announced Monday.

The "preventive measure" is based on "directives from the foreign and health ministries to avoid" the spread of Ebola to the kingdom, the official news agency SPA reported.

The virus, for which there is no treatment or vaccine, has claimed 1,552 lives out of 3,069 reported cases -- 694 in Liberia, 430 in Guinea, 422 in Sierra Leon and six in Nigeria, according to latest figures from the World Health Organisation.

Saudi Arabia made a similar decision in April when it announced the suspension of visas for Muslim pilgrims from Guinea and Liberia.

The hajj annual pilgrimage, the world's biggest Muslim gathering, draws two million people to Saudi Arabia each year, including many from the West African countries affected by the Ebola outbreak. This year it falls in October.

The "temporary suspension" of labour visas from the three African nations "will not affect the labour market in Saudi Arabia" where the number of workers from these countries "is very little," SPA quoted deputy labour minister Mufrej al-Haqbani as saying.

He said laboratory tests before arrival were "strictly required" by the labour ministry for all foreigners coming from west Africa.

Apart from Nigeria, Ebola has also spread to Senegal.