The US government says Syrian forces under President Bashar al-Assad have used chemical weapons "on a small scale" against the opposition rebels.

A senior aide to President Barack Obama said the US estimated 100-150 people had died in "multiple" attacks.

Ben Rhodes said the president had decided to provide unspecified "military support" to the opposition.

The White House had previously warned that the US considers the use of such weapons, as crossing a "red line".

Mr Rhodes, a deputy national security adviser to Mr Obama, said the US had no "reliable" evidence the opposition had used chemical weapons.

Earlier, the United Nations said the number of those killed in the Syrian conflict had risen to more than 93,000 people.