Washington, Apr 6 (IANS): US President Donald Trump has said the chemical attack against Syrian civilians that killed over 70 people "crossed a lot of lines for me" and changed the way he views Syria and President Bashar al-Assad.

"I now have responsibility, and I will have that responsibility and carry it very proudly," Trump said on Wednesday at a press briefing responding to a question about a White House statement on Tuesday that blamed the attack in part on former President Barack Obama.

"It is now my responsibility. It was a great opportunity missed," CNN quoted Trump as saying.

The President condemned the attack as "heinous".

"Yesterday's (Tuesday) chemical attack was so horrific in Syria against innocent people, including women, small children and even beautiful little babies, their deaths were an affront to humanity," Trump said.

"These heinous actions by the Assad regime cannot be tolerated. The US stands with our allies across the globe to condemn this horrific attack."

World leaders expressed shock and outrage at reports of the suspected targeted attack in northwestern Syria.

Activists said the Syrian regime was responsible for killing dozens of people, including many children, leading the UN to replace a scheduled Security Council session for Wednesday morning with an emergency meeting, reports CNN.

Assad's military denied using chemical weapons and blamed rebels for the carnage. Russia, Syria's strong ally, said it had no warplanes in the vicinity.

Rex Tillerson, Trump's Secretary of State, said there was "no doubt in our mind that the Syrian regime under the leadership of President Assad is responsible for these horrific attacks."

He called on Russia to "really think carefully" about their continued support for Assad's regime in Syria.