Mr Brahimi said the talks would be continuing, and that it was hoped that some changes to help people on the ground in the bloody civil war could be agreed on Sunday.
A humanitarian convoy could be allowed to move into the besieged city of Homs as early as Monday, if talks progress as planned. He added that planned prisoner releases would also be discussed on Sunday.
UK arrests
Meanwhile in the UK, the head of the Association of Chief Police Officers has warned that Britons who travel to Syria could be arrested on their return.
Peter Fahy said there was a “huge concern” about Britons being radicalised if they travel to Syria, especially if they are doing so to fight.
British police have already arrested 16 people on suspicion of terrorism offences in Syria this year, some as young as 17, compared to 24 arrests in all of 2013.
“We stopped quite a number of people because we’re very, very clear about what will happen,” Mr Fahy told BBC Radio.