The leader of the opposition Syrian National Coalition (SNC) has called for the creation of a unified rebel army that works under the command of the Free Syrian Army (FSA) chief of staff.

Speaking to Al Jazeera on Monday, Ahmed al-Jarba said that rebels need to unify in one force because "the rules of the game has changed" after the involvement of the Lebanese Hezbollah movement in the Syrian conflict.

"There are a number of Hezbollah fighters inside Syria. They are trained and have advanced weapons," Jarba said.

He said a rebel force is needed "that includes the elite so we deal with the groups that infiltrate to Syria".

'All welcome'

Jarba said the "National Free Army" would be under the supervision of the FSA chief of staff General Salim Idriss and under the umbrella of the SNC.

He described the current situation in eastern Syria, where rebel groups have taken control of big areas, as "chaotic"

"There is chaos in the eastern areas and there’s chaotic selling of oil" Jarba said.

"We will try to include all fighters in the National Army, all the loyalists and revolutionaries are welcome .. But there should be order restored and work should be institutionalised ... We will not exclude anyone".

Unrest in Syria began with protests in March 2011 and later turned into a civil war. More than 100,000 people have been killed in the conflict, according to the opposition and the UN.