Syria’s foreign minister has warned that if foreign powers do strike the Middle Eastern nation, the government and its forces will fight back.

"Syria is not easy to swallow," said Walid Moallem. "We have the materials to defend ourselves. We will surprise others."

"We all hear the drums of war. They want to attack Syria. I believe to use chemical weapons as a pretext is not a right."

Moallem said Tuesday that his government would never use such munitions against its own people, daring those who disagree to present evidence publicly.

He said rebel forces were to blame for security concerns near the suspected chemical sites, arguing that Western leaders are using the claims as an excuse to go after al-Assad's regime.

Meanwhile US Defence Secretary Chuck Hagel said the military is "ready to go" in responding to Syria.

UN weapons inspectors are set to return to the site of last week's suspected attack near Damascus on Wednesday.

Their evidence-gathering visit was delayed by a day after they were fired on.

The United States, meanwhile, is conducting its own investigation. The intelligence report will include forensic evidence and intercepted communications among Syrian military commanders, according to unnamed officials, cited by CNN.