U.S. Secretary of State Hillary Clinton speaks to the media about Syria after her meeting with Norway's Foreign Minister Jonas Gahr Stoere at the State Department in Washington August 12, 2011. (Xinhua/Reuters)

U.S. Secretary of State Hillary Clinton on Friday called on nations to cut their business ties with Syria, stoking up pressure on Syrian President Bashar Assad.

"We urge those countries still buying Syrian oil and gas, those countries still sending Assad weapons, those countries whose political and economic support give him comfort in his brutality, to get on the right side of history," the top U.S. diplomat told reporters at the State Department after meeting with Norwegian Foreign Minister Jonas Gahr Stoere.

Assad has lost his legitimacy to lead and "it is clear that Syria would be better off without him," Clinton said.

A day earlier, she told the CBS TV network that the U.S. was seeking "to sanction the oil and gas industry" of Syria, and the U. S. was hopeful for European steps in that direction. She also called on Russia to stop selling arms to Syria.

The U.S. on Wednesday imposed additional sanctions on Syria by targeting its largest commercial bank and largest mobile phone operator, in its efforts to force Syria to stop the intensifying crackdown on protesters.

However, Assad vowed that his country "will not waver" in its pursuit of terrorist groups, which Syria blamed for the unrest in the country starting in mid-March.