Defence lawyers have started cross-examining the State's star witness in its case against former police commissioner Jackie Selebi in the South Gauteng High Court.

Glen Agliotti has completed his evidence-in-chief.

Agliotti was on his guard as Selebi's advocate Jaap Cilliers began his cross-examination.

He conceded when Cilliers put it to him that he had given the former police commissioner the impression he was a generous philanthropist.

The defence then poked its first hole in the State's case, as Agliotti denied Selebi had protected him from being arrested for his involvement in a major drugs bust in Kya Sands in 2002.

That claim forms one of the prosecutions' key charges against Selebi.

Earlier, Agliotti broke down in tears as he spoke about how difficult it has been to testify against his "old friend".

When Selebi was still police chief he famously said Agliotti, who is a self-confessed drug trafficker, was his friend "finish and klaar".