ISTANBUL: A group claiming to represent the majority of the opposition movements inside Syria declared Thursday the foundation of a "National Alliance" of revolutionary forces aiming to topple the regime.

"The regime has killed, maimed, arrested, tortured and displaced tens of thousands of people," Mohammed Bessam Imadi, a former Syrian ambassador to Sweden, told a press conference in Istanbul.

"Therefore different revolutionary groups sought to unify their operational and political leadership to join forces and overthrow the regime," added Imadi, who described himself as head of the alliance.

"Now that the time is ripe, it has become necessary to declare our existence publicly. Therefore, we announce the National Alliance of Forces, Coordinators and Councils of the Syrian Revolution; Al-Leeqa," he said, reading a statement.

The former diplomat said Al-Leeqa includes "the majority of revolutionary groups conducting the revolution in Syria."

"We have managed to gather all these groups under the same umbrella," he said.

The Syrian National Council (SNC), which has brought together dissidents from inside and outside Syria, has recognised Al-Leeqa as one of its components.

Imadi told reporters that Al-Leeqa supported the Free Syrian Army, a grouping of army deserters that has taken up arms against the forces loyal to President Bashar al-Assad, "as long as it protects civilians and the peaceful revolution in Syria."

Questioned by AFP, Imadi said Al-Leeqa was a stucture uniting most of the local coordination committees in Syria, which were organizing protest movements in districts and cities.

"Only a small number of local coordination committees were represented" in the SNC, Imadi said, adding that the SNC then "lost contact with local revolutionary movements in Syria," implying that they would re-establish that tie.

The announcement came as the uprising in Syria entered its 10th month, with increasing attacks by rebel soldiers on security forces held responsible for the regime's heavy crackdown on civilian protest.

The United Nations human rights chief Navi Pillay said this week the death toll had exceeded 5,000.