Speaking at a news conference following a fact-finding trip to South Ossetia, Josi Dubie said: "We must by all means prevent Georgia from becoming a NATO member due to its belligerent and aggressive policy. We do not want to be part of that policy."
Fellow senator, Christine Defraigne, who also visited the region, said admitting Georgia to the military alliance would be "reckless and insane."
At its summit in Bucharest in April, NATO decided to put off the decision on whether to grant membership action plans to Georgia and another ex-Soviet republic, Ukraine, until December. Their bids have received strong U.S. backing, but Germany and France said that opening the path to membership for the two states would unnecessarily antagonize Russia.
Any decision to admit new members to the military alliance requires the unanimous approval of all NATO members.
Dubie, deputy head of the Senate's commission on foreign affairs and defense, said the recent five-day war between Russian and Georgia was, without question, started by Georgia.
"As to who was the aggressor, we can say without hesitation that it was Georgia," Dubie said, adding that "disinformation on the issue is unacceptable."
Russia launched a military operation to "force Georgia to peace" after Georgian troops attacked Tskhinvali, the capital of South Ossetia, on August 8.
The majority of Western states criticized Russia's use of force against Georgia and condemned its subsequent move to recognize South Ossetia and Georgia's other breakaway territory, Abkhazia. Tbilisi has claimed Russia was the first to attack, although it has supplied no proof to back up its claims.
A number of Western media outlets also provided what Russian commentators have called "biased" reports of the conflict.
Russia Prime Minister Vladimir Putin criticized the U.S. stance on the conflict, saying, "The very scale of this cynicism is astonishing - the attempt to turn white into black, black into white and to adeptly portray victims of aggression as aggressors and place the responsibility for the consequences of the aggression on the victims."
The Belgian lawmakers said after visiting Tskhinvali that the death toll of 1,500 residents announced by South Ossetian authorities seemed to be a realistic estimate.
"The city resembles Beirut. This is unthinkable!" Defraigne said, adding that Russia's counterattack was understandable.
South Ossetia and Abkhazia both broke away from Georgia after the collapse of the Soviet Union in 1991. Both republics fought vicious wars with Tbilisi that eventually ended in the retreat of Georgian troops and the regions gaining de facto independence.
