Heat resistant anti-retroviral HIV-AIDS drugs manufactured in the United States have arrived in Nigeria, Africa's most populous country, Medecins Sans Frontiers (Doctors Without Borders), said on Thursday.

The new version of the fixed-dose combination lopinavir/ritonavir (CPV/R), marketed as Kaletra by Abbott Laboratories, was approved for use last October.

On March 15 MSF had placed an order for the new drug with Abbott headquarters in the United States to use in MSF projects in nine countries: Cameroon, Guatemala, Kenya, Malawi, Nigeria, South Africa, Thailand, Uganda and Zimbabwe, it said.

The organisation stressed the need for Abbott to take necessary actions to register the drug and make it affordable in Nigeria, the country which has 3.5 million AIDS sufferers, placing it the second most hit in Africa, after South Africa.

Last April Abbott announced a price for the new formulation of 500 dollars per patient per year for least developed and African countries.