The UK government has still not decided whether to arm the Syrian rebels, Downing Street has said.
The White House has announced it will supply direct military aid, having concluded that the Syrian regime is using chemical weapons.
Tory MP John Baron urged David Cameron not to rush to follow suit and Labour says efforts should be on peace talks.
Downing Street said on Friday "no decision has been taken" on supplying arms but "nothing is off the table".
The prime minister's spokesman did not rule out the introduction of a no-fly zone over Syria, or any other measure, adding: "We are in urgent discussions with our international partners".