GENEVA (AFP) - A controversial member of the powerful Army of Islam rebel group said Sunday he was coming to Geneva to serve as the Syrian opposition's lead negotiator in thorny UN-brokered peace talks.

"I'm on the way. I will be the chief negotiator," Mohammed Alloush said, adding that he expected to arrive in Geneva before noon on Monday.

The main opposition umbrella group, the High Negotiations Committee (HNC), controversially appointed the Islamist chief as its lead negotiator earlier this month.

The choice of Alloush, the political leader of the Saudi-backed armed group Jaish al-Islam, or Army of Islam, has sparked an outcry.

Syria's ally Moscow has slammed the appointment, saying it considers Jaish al-Islam as "terrorists" and other opposition groups insisted it was unacceptable for the delegation to be led by a member of an armed group.

Other members of Jaish al-Islam had reportedly arrived in Geneva with other HNC delegates late Saturday, but it had remained unclear if Alloush himself would actually join the troubled negotiations which have yet to get started in earnest.

The indirect talks on ending Syria's nearly five-year conflict had been scheduled to start on January 25, but were postponed until the 29th, when the Syrian government delegation sat down with UN mediator Staffan de Mistura.

But the HNC has until now been debating whether to formally engage in the process, demanding that humanitarian aid first gets through to besieged towns, that the bombing of civilians ceases and that hundreds of prisoners are released.

Both delegations were to meet separately with de Mistura Monday, the UN said, sparking hope the talks might finally get moving.

The opposition delegation was to meet with the UN envoy at 5 pm (6 am Singapore time), but it was unclear whether Alloush would take part in that meeting.