By Susannah Price
BBC correspondent, United Nations
The head of the UN inquiry into the murder of former Lebanese PM Rafik Hariri says improved co-operation from Syria is critical to its success.
The investigation commission's mandate ends in June
Chief investigator Serge Brammertz told UN Security Council members he had been given permission to meet Syria's president in the coming month.
Mr Brammertz also said a number of new leads had led to "faster than expected progress" in certain important areas.
Mr Hariri was killed in a massive car bomb in Beirut in February 2005.
The previous UN chief investigator, Detlev Mehlis, had accused Syria of failing to co-operate and said this had impeded the investigation.
Mr Mehlis had also concluded that Mr Hariri, a critic of Syria's involvement in Lebanon, could not have been killed without the knowledge of Syrian and Lebanese officials.
Syria said it was not involved in the assassination and that it is co-operating.
The investigation commission's mandate ends in June and Mr Brammertz warned they could not guarantee that their work would be finalised in a few months.