In April 2005, the UN Security Council set up a commission to investigate the assassination of Hariri, who was killed in a truck bombing February 14, 2005.
"The latest actions of the commission showed that investigation under the 'Hariri dossier' had failed to produce the expected results," Buthaynah Shabaan said at a RIA Novosti news conference.
Shabaan is in Moscow along with the late prime minister's son, Lebanese parliament majority leader Saad Hariri, on a five-day visit. President Vladimir Putin met with Saad Hariri Friday as part of Russia's efforts in the Middle East peace process.
The UN investigation commission has recommended the arrest of four top security officials in Syria's Damascus, and implicated officials in Beirut. Syria has strongly denied any involvement in the killing.
Shabaan declined to comment on the work of the head of the international inquiry commission, Serge Brammertz, who visited Syria in April and met with Syrian authorities, including President Bashar al-Asad.
"I do not have full information yet, but as far as I know, Brammertz is to present his report on June 15, and I would not like to make any conclusions before then," she said.
She also said that two days after Brammertz visited Damascus on April 25, the United States decided to freeze the accounts of several Syrian citizens suspected of involvement in the Hariri killing.
"It could be just a coincidence. But we would not want the investigation to act this way when suspects become defendants and almost immediately convicts," Shabaan said.
As to a possible international tribunal for the Hariri assassination, she said there was still no evidence.
"I do not think that any evidence against Syria will appear," she said.
Hariri's death prompted Syria to withdraw its troops, which had been deployed in Lebanon for nearly 30 years, under intense international pressure.