The Truth and Reconciliation Commission in South Africa has begun hearing evidence of he country's chemical and biological warfare programme during the apartheid era.

The commission will try to establish the extent of the programme -- and discover whether it was sanctioned by the former apartheid government or was the work of renegade groups within the security services.

The BBC Southern Africa correspondent says evidence already collected by the commission indicates the widespread use of deadly viruses and chemical irritants against government opponents; in some cases poisoned-tipped umbrellas and beer bottles infected with viral agents were used.