WASHINGTON (AFP) - Syrian President Bashar al-Assad warned Washington on Monday to brace for retaliation if US forces attacked his war-torn country, as he denied using chemical weapons against his people.

"You should expect everything ... The government's not the only player in this region. You have different parties, different factions, different ideologies. You have everything in this decision now," Mr Assad told CBS television's "This Morning."

He spoke in what CBS called his first interview since US President Barack Obama asked Congress for approval to use military force to punish Mr Assad for his regime's alleged use of chemical weapons in a deadly attack last month.

Mr Assad denied such an attack by his forces.

"How can you talk about what happened if you don't have evidence?" he said in the interview, which he gave in English.

He was asked if the "everything" he predicts might break out if America attacks could include the use of more chemical weapons.

"That depends. If the rebels or the terrorists in this region or any other group have it, it could happen. I don't know. I'm not a fortune teller to tell you what's going to happen," Mr Assad said.

Mr Obama will on Tuesday address Americans from the White House to discuss intervention in Syria, ahead of a possible Senate vote on authorising force against Mr Assad's regime later this week.