A missile strike in response to chemical weapons use in Syria would be within the framework of international law and does not need the unanimous support of the UN security council, according to British foreign secretary William Hague.

As UN weapons inspectors get ready to inspect the site of the alleged chemical attack strongly attributed to the Assad-led regime, Hague reiterated calls for a strong international response to the attack in Damascus' eastern outskirts of Ghouta that killed at least 355 people and injured 3,600.

"Is it possible to respond to chemical weapons without complete unity on the UN Security Council? I would argue yes it is, otherwise it might be impossible to respond to such outrages, such crimes, and I don't think that's an acceptable situation," Hague said on BBC radio.

"Whatever we do will be in accordance with international law and will be based on legal advice to the national security council and to the cabinet," he added.

The UN Security Council has been hamstrung by vetoes from Russia and China.

Hague's remarks came after British media reported that missile strikes could take place within days.

A 40-minute phone call between prime minister David Cameron and US president Barack Obama allegedly resulted in both countries discussing taking military action against Assad for the Ghouta chemical attack.

Royal Navy vessels are poised to take part in a possible series of cruise missile strikes on Syria, according to the Daily Telegraph.

Turkish foreign minister Ahmet Davutoglu said Ankara would join an international coalition against Assad if the UN security council could not reach a consensus.

However, Obama - who also spoke with French president Francois Hollande and Australian prime minister Kevin Rudd - is still undecided on taking action.

A senior Obama administration official said there was little doubt that Assad's military forces had used chemical weapons against civilians. He claimed that Assad's decision to allow UN inspectors access to the site was "too late to be credible".