U.N. expert: More arms for Syria mean more war crimes...

(Reuters) - Increasing the flow of weapons to Syria's government and rebel forces will most likely cause an increase in war crimes in a two-year-old civil war that has killed more than 90,000 people, a U.N. human rights investigator warned on Friday.

"States who provide arms have responsibilities in terms of the eventual use of those arms to commit ... war crimes or crimes against humanity," said Paulo Pinheiro, who chairs a U.N. commission of inquiry on rights violations in Syria.

"Those arms will contribute to the escalation of war crimes," he told reporters. "We are very much worried that more arms will signify an increasing presence of those violations."

U.S. President Barack Obama decided a week ago to provide military aid to rebels trying to overthrow Syrian President Bashar al-Assad, citing his government's alleged use of chemical weapons.

Earlier this month Pinheiro said in a report to the U.N. Human Rights Council in Geneva that his team had reasonable grounds to believe that limited amounts of chemical weapons had been used in Syria and warned that the country was in "free-fall".

His team's report said it had received allegations that Syrian government forces as well as rebels had used the banned weapons, but most testimony related to their use by state forces.

Pinheiro reiterated those findings in New York on Friday when he spoke to reporters after addressing an informal U.N. Security Council session on the report.

Assad's government denies using chemical weapons in the conflict but has accused the opposition forces of using them.

Siria e la Russia, uno dei principali fornitori di armi di Assad insieme con l'Iran, hanno accusato Stati arabi del Golfo Arabia Saudita e Qatar, così come la Gran Bretagna e la Francia, di armare i ribelli.

The European Union last month lifted its arms embargo on Syria. Britain and France have spoken in favor of potentially arming the rebels but say they have taken no decisions to do so.

(Reporting by Louis Charbonneau; Editing by Xavier Briand)