DAMASCUS - A Syrian government minister said U.S.-led air strikes against militants are going in the "right direction" because the government had been informed before they started and they were not hitting civilians or Syrian military targets.

Syria is still watching all developments with caution, Ali Haidar, minister for national reconciliation, told Reuters on Wednesday after U.S. warplanes pounded Islamic State positions in a second day of attacks.

"As for the raids in Syria, I say that what has happened so far is proceeding in the right direction in terms of informing the Syrian government and by not targeting Syrian military installations and not targeting civilians," he said.

"Notification of the Syrian government happened," he said. "Confirmation that they would not target Syrian military installations, and confirmation they would not target civilians happened."

The United States said on Tuesday that Washington's envoy to the United Nations had told her Syrian counterpart air strikes would take place, but it has ruled out coordinating with Assad, whom Washington sees as part of the problem.

The Syrian foreign minister said last month that Damascus was ready to cooperate in any international effort to fight Islamic State.

Despite welcoming the strikes, Haidar said fighting militants would take more than such military action.

"The war on terror does not only come through air strikes, which are not the only means to fight terrorism," he said, adding that military action could go on for some time.

The Syrian government has described all insurgent groups in Syria as "terrorists", from the Western-backed rebel opposition to Islamic State fighters who have seized tracts of territory in the country and in neighbouring Iraq.