NSC secretary-general Paradorn Pattanatabut said that security agencies were still studying the separatist group's demands and had yet to reach a decision.
The government was particularly concerned about demand No.4, which would require the authorities to acknowledge the rights of the "Melayu Patani" people to the so-called "Patani land", he said.
The BRN's fifth demand calling on the government to free all suspects in southern security cases was also impossible for the government to decide about alone, Lt Gen Paradorn said.
The issue involved several parties and was subject to the rule of law.
An online report published by Deep South Journalism School, a media training programme run by NGO Deep South Watch, quoted a Malaysian source as saying the Thai government had already accepted four out of the five BRN demands.
According to the article, the Malaysian source said he was informed by chief BRN negotiator Hassan Taib on Sept 5 that Thailand had accepted the four demands.
The BRN issued its five demands in a video clip posted on YouTube in April.
The three other demands were the government's recognition of the BRN as a liberation group rather than separatists; the recognition of Malaysia as the peace talks mediator instead of the facilitator; and for Asean member countries, the Organisation of Islamic Cooperation and international NGOs to witness the talks.
Lt Gen Paradorn said the committee responsible for solving problems in the South met Thursday and discussed a 34-page document submitted to the government by the BRN to clarify the demands.
The meeting was chaired by deputy prime minister Pol Gen Pracha Promnok, who is in charge of implementing the government's policies to resolve the southern unrest.
The Internal Security Operations Command and the Southern Border Provinces Administration Centre were analysing the document, Lt Gen Paradorn said. They were expected to come up with conclusions before the next round of peace talks, set for the third week of next month.
The study of the demands was about 90% complete but Lt Gen Paradorn said he could not discuss the findings so far.
Lt Gen Paradorn said even if the BRN's demands were accepted, more talks would be needed before they could be implemented.
He said the NSC planned to question the BRN about numerous insurgent attacks during Ramadan.
The BRN had promised to refrain from using violence during the Muslim holy fasting month.
The council would also ask the BRN to stop publicising their peace talks messages and instead convey them through the proper channels, Lt Gen Paradorn said.
Meanwhile, three military rangers were killed and one wounded in an attack by gunmen in Pattani's Yarang district Thursday morning.
The attack occurred about 11.30am when six members of Ranger Company 2208 were repairing the roof of a local's house in Binya village in tambon Khlong Mai, part of a winning hearts and minds operation.
Seven or eight armed men arrived at the house in a black Toyota pick-up truck and opened fire on the soldiers.
The rangers returned fire and the gunfight lasted about five minutes.
Three of the rangers were killed and one wounded in the clash. The attackers fled with two weapons they stole from the dead rangers.
The attack happened a day after assailants shot dead five police officers in Pattani's Thung Yangdaeng district.
National police chief Adul Saengsingkaew said officers had found a link between weapons used in Wednesday's shooting of the five police officers and several other attacks in the region.
A preliminary investigation showed that Wednesday's attack was likely to be linked to an illegal oil trafficking ring operating in the South, Pol Gen Adul said.