Turkish Foreign Minister Davutoglu said Syrian President Bashar al- Assad has crossed the red line several times.
Davutoglu attended Newsnight's program of BBC during his visit to London.
Assad started with snipers to kill people and continued to use artillery shells and scud missiles and lastly chemical weapons, said Davutoglu.
He criticized the international community and said, “Unfortunately the international community did not respond in an effective way."
"In the last 24 hours after this chemical attack, there has been mobility in the international community. We called several allies including Britain for an emergency meeting of UN Security Council for extending the mandate of chemical expert team of the UN in Damascus. There was an emergency meeting of the UN Security Council but it was not very effective, decisive and firm, " Davutoglu said.
"This is a test for Assad, and for countries that have been supporting him. Assad claims he didn't do it. Then, he must allow the UN team to search. If he rejects the UN call, then there should be a decisive, firm position of the UN Security Council."
Davutoglu said UN Secretary General Ban Ki-moon has said the alleged chemical weapons attack near the Syrian capital "needs to be investigated without delay".
At least 1,300 were killed in a chemical weapons attack staged by the Syrian regime in the suburbs of the Ghouta region near Damascus in the early hours of Wednesday, which the Syrian government strongly denies.