DAMASCUS -- Washington had informed Syria of airstrikes against positions of the Islamic State (IS) in Syria before the strikes started, the Syrian Foreign Ministry said in a statement Tuesday.

The statement said that Syria's envoy to the United Nations was informed on Monday about the commencement of the US-led airstrikes against IS positions in Syria's northern province of al-Raqqa, adding the airstrikes started before daybreak Tuesday.

The ministry didn't mention the Syrian government's response to the airstrikes.

The opposition Syrian Observatory for Human Rights said the United States launched 20 rounds of airstrikes in al-Raqqa and its surroundings region.

Abu Muhammad al-Raqqawi, a local activist, told foreign media that the first strike targeted the al-Tabaqa military air base, which had been captured by the IS recently.

Other activists said tens of the IS fighters were either killed or injured in the strikes.

Washington and its partners have begun striking IS targets in Syria with a mix of fighters, bombers and Tomahawk missiles, according to the Pentagon.

Saudi Arabia, Jordan and the United Arab Emirates have reportedly participated in the airstrikes.

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