Syrian opposition members met for a fourth day in the Saudi capital on Friday but had still not announced whether they would join peace talks beginning the same day in Geneva.

The Saudi-backed High Negotiations Committee (HNC) has said it will not attend the negotiations with the Syrian regime until an agreement is reached on aid entering besieged towns.

"Nothing new," a senior delegate from the Committee said shortly before noon after leaving the meeting room at a luxury hotel in the Saudi capital.

Another delegate had said on Thursday night that he believed "tomorrow we will take a decision" on whether to attend the UN-brokered negotiations.

HNC coordinator Riad Hijab said aid access was a precondition of the group attending the Geneva negotiations between the opposition and government of Syrian President Bashar al-Assad.

"Tomorrow we won't be in Geneva. We could go there, but we will not enter the negotiating room if our demands aren't met," he told Al-Arabiya television late Thursday.

A spokeswoman for the UN-brokered talks, Khawla Mattar, said that no postponement was planned.

The HNC has asked for "clarifications" after the UN issued invitations to other opposition figures.

The Committee insists that it is the sole permitted representative of Syria's opposition, despite objections from others.

It also wants assurances from the international community that it will move to end regime attacks on civilians and allow humanitarian aid.

The HNC was formed in December when the main Syrian political opposition and armed factions came together in Riyadh for an unprecedented bid at unity, after months of Saudi efforts.