Lebanon is now "hostage" to Syria and Hezbollah following the formation of a cabinet in which the Iranian- and Syrian-backed militant party and its allies form the majority, an opposition leader told AFP on Tuesday.

"We denounce the formation of this government and state that Lebanon is a country now being held hostage by the Syrian regime and Hezbollah," said Fares Soueid, a former MP and general coordinator of the pro-Western "March 14" opposition.

Soueid said the opposition would formally issue a press release this week stating their position against the cabinet of Najib Mikati.

Mikati on Monday announced the formation of a government in which Hezbollah and its allies control 18 out of 30 portfolios, including the key justice and telecommunications ministries.

The March 14 alliance, led by US- and Saudi-backed former premier Saad Hariri, has refused to join the government.