Punishments - including executions - are carried out in public
At a meeting in Geneva, the committee said such penalties violated international conventions against cruel and degrading treatment.
It recommended that the Saudi authorities re-examine their penal code.
The criticism was presented to Saudi delegates who immediately rejected it, saying Sharia law expressly forbade torture.
It is the first time Saudi Arabia has reported to the committee.
All signatories to the Geneva conventions are required to inform the committee about their records in upholding international laws on the treatment of prisoners.
Long-established practice
The BBC correspondent in Switzerland, Imogen Foulkes, says it is perhaps not surprising that Saudi Arabia came in for criticism, given its well-known policy of corporal punishment.
But the Saudi delegation in Geneva said it could not accept interference in its legal system, aspects of which have been practised in the region for more than 1,400 years, it said.
The committee dismissed Saudi protestations that Shari law expressly prohibited torture, pointing out that if this was the case it was not reflected in Saudi Arabia's domestic law.
The human rights group Amnesty International issued a major report on Saudi Arabia in 2000.
It said the kingdom was guilty of widespread human rights abuses, with the silent consent of western powers which are reliant on Saudi oil.
Amnesty said the criminal justice system facilitated torture - often to extract confessions and enforce discipline - while lack of judicial supervision, denial of access to relatives, doctors and lawyers leave prisoners extremely vulnerable to abuse.