WASHINGTON - The US State Department on Monday urged the Syrian opposition to stick to peaceful means as a number of prominent academics have recently been assassinated in the Middle East country gripped by unrest.

"I think one of the things that we would particularly note about this group is that it has called for non-violence and for a peaceful transition, which is obviously something that we support, " State Department spokesperson Victoria Nuland said when asked to comment on the formation of a Syrian opposition group's leadership in Turkey's largest city of Istanbul on Sunday.

"We are continuing to urge the Syrian opposition to make their views known peacefully to the extent that they can," she said.

Syria has recently seen nine assassinations of the country's prominent academics. In the latest incident, Mohammad al-Omar, a history professor at Aleppo University, was gunned down on Sunday by unidentified gunmen, along with Saryah Hassoun, son of Syria's grand mufti Ahmed Hassoum, a staunch supporter of the Syrian government.

No one has taken responsibility for the killings. But Syrian government and Syrian oppositions are trading accusations, each of them holding the other accountable for the murders.

Nuland said that the formation of the leadership of the Syrian opposition group in Istanbul "is the latest in an effort of many different Syrian opposition groups to try to unite."

"We've been encouraging all the groups to try to unite under one umbrella, so we're obviously encouraged by any effort to bring more unity," she said.

Syria's opposition agreed in principle Sunday to form a seven- member executive committee for their national council following three days of deliberations behind closed doors in Istanbul.