BEIRUT – The Syrian government agreed Sunday to allow United Nations inspectors to visit the sites of suspected chemical-weapon attacks outside Damascus – a move U.S. officials called “too late to be credible.”

The reported accord comes as U.S. officials were said to be preparing for a possible military strike on Syria in retaliation for the government’s alleged use of chemical weapons.

The Syrian government has denied using chemical weapons in a series of alleged attacks that occurred early Wednesday against opposition strongholds outside of Damascus.

Opposition representatives have accused the government of mounting poison-gas bombardments, killing hundreds, including women and children.

Unverified video said to be of the victims has caused global outrage and prompted calls for an independent inquiry.

Experts have said the images are not conclusive but could indicate the deployment of a nerve agent of some kind and have stressed the need for on-site inspection and the taking of samples from the area and from purported victims. Officials have said time is of the essence as some of the suspect substances may dissipate in a few days, making detection more difficult.

Syrian authorities have said that any chemical attacks were carried out by rebels, to discredit the government and prompt international retaliation against Syria. The Syrian opposition has denied using any chemical weapons.

On Sunday, Syrian state media reported that government officials and the U.N. “have agreed to a mutual understanding that enters into force immediately allowing the U.N. inspection team to investigate” the sites of the recent alleged attacks.

President Obama met with his top security advisers this weekend about the Syria crisis, signalling that the administration was leaning toward a military intervention in the two-year-old civil war.

But any strike against Syrian President Bashar Assad’s regime would occur over the misgivings of a majority of Americans, according to a new poll, and with only limited support from Congress. The fallout from such action includes likely retaliation from Iran, Russia and the Lebanese militant group, Hezbollah – Assad’s three chief foreign patrons – and could draw the United States deeply into a new Middle East conflict after years of entanglement in Iraq and Afghanistan.

However, many foreign policy analysts argue that after more than two years and a death toll exceeding 100,000, Obama has a moral imperative to step in now because of the escalation from the regime’s apparent use of chemical weapons in defiance of his warning that such warfare was a “red line.”

Statements from the administration over the weekend suggest that Obama’s extreme reluctance to wade into the crisis was easing, though there were no details yet on a course of action as U.S. officials continued consultations with European and Arab allies.

Obama appeared to be shoring up international support for action Sunday, speaking with his second ally in two days, French President Francois Hollande. The White House said the two discussed “possible responses by the international community” and agreed to stay in touch.

At a news conference Sunday in Malaysia, Defense Secretary Chuck Hagel reiterated that he’d prepared “options for all contingencies” at Obama’s request.

A senior administration official, speaking Sunday on the condition of anonymity, dismissed Syria’s “belated decision,” saying that the regime obfuscated for so long that now “the evidence available has been significantly corrupted as a result of the regime’s persistent shelling and other intentional actions over the last five days.”

“There is very little doubt at this point that a chemical weapon was used by the Syrian regime in this incident,” the official said, citing the high number of casualties, victims’ symptoms, eyewitness accounts and the intelligence assessments of the U.S. and its allies.

A 20-member contingent of U.N. inspectors is already in Damascus, but the team’s official mandate was limited to looking into three previous allegations of chemical weapons use in Syria.

Sunday’s agreement would seem to open the way for the experts to visit several areas near the capital where chemical weapons allegedly struck last week.

The United Nations and individual member nations, including the United States and Russia, have been pressing Damascus to allow the experts to visit the disputed sites.

The U.N. staff “should coordinate with the Syrian government on the date and time of the team’s visit to the sites agreed to by the two sides,” the Syria news media said.

The areas allegedly hit by chemical gas attacks are in conflict-ridden suburbs of Damascus where government troops and armed rebels have repeatedly clashed. Officials would have to agree on some kind of security regimen and possibly a cease-fire to permit the U.N. presence. Opposition activists have said they are willing to facilitate the entry of U.N. personnel.

Syrian Foreign Minister Walid al-Moallem said his government was ready to cooperate with the U.N. to “expose the false allegations of the terrorist groups accusing the Syrian forces of using chemical weapons.” Syrian authorities routinely refer to armed rebels as terrorists.

– The Los Angeles Times and McClatchy Newspapers contributed to this report.