MOSCOW — Russia dramatically escalated its denunciations of American threats to attack Syrian military targets on Saturday, with President Vladimir Putin saying it would have been ‘‘utter nonsense’’ for the Syrian government to use chemical weapons as the Obama administration alleges.
The Foreign Ministry, in a statement issued before President Obama said he would seek congressional authorization before ordering strikes on Syria, said a US attack would be a ‘‘gross violation’’ of international law.
Speaking out for the first time since an apparent chemical weapons attack near Damascus 10 days ago, Putin called on Obama to find a nonviolent way to resolve the crisis.
‘‘I would like to address Obama as a Nobel Peace Prize laureate: Before using force in Syria, it would be good to think about future casualties,’’ Putin told Russian news agencies in Vladivostok during a tour of the nation’s flood-stricken Far East.
‘‘Russia is urging you to think twice before making a decision on an operation in Syria,’’ he said.
In Paris, a presidential official said France will wait for discussions on Syria in the US Congress and French Parliament before making a decision on military intervention, the Associated Press reported.
The official said President Francois Hollande spoke with Obama on Saturday and the two agreed to act together on Syria.
The French Parliament was already planning to convene Wednesday about Syria, but Hollande does not need its permission to intervene militarily.
In London, more than 1,000 protesters carrying Syrian flags and placards marched to Downing Street and rallied in Trafalgar Square. Some hailed the Parliament’s vote Thursday against British participation as a victory. Prime Minister David Cameron said Saturday in a Twitter message that he supported Obama’s decision.
About 700 people turned out for an antiwar march in Frankfurt, Germany, police said.
Egypt’s Foreign Minister Nabil Fahmy said Cairo rejects military intervention in Syria except under Chapter 7 of the UN charter, which requires proof that the country has become a danger to international peace and security.
UN inspectors left Syria on Saturday after four days of efforts to investigate the Aug. 21 chemical attack in Syria that US officials said killed more than 1,400 people.
The inspectors headed to The Hague with blood and urine samples taken from victims of the attack, as well as soil samples from areas where the attacks occurred. The samples will be divided and sent to at least two separate European laboratories for testing.
Angela Kane, the UN disarmament chief, briefed UN Secretary General Ban Ki-moon on Saturday and reported that inspectors were “able to conduct a wide range of fact finding activities,” according to Martin Nesirky, the secretary-general’s spokesman. Nesirky repeated that the inspectors’ mandate was to find out whether chemical weapons were used, not who was responsible.
He said the inspection team would not transmit its report to the UN chief until it had lab results.
The White House argued Friday that intelligence shows the estimated 1,400 victims died from exposure to chemical weapons in an attack carried out by the Syrian military.
The Syrian government had asked the UN team to extend its mission to investigate its claims of rebel attacks involving chemical weapons — a request widely seen as a stalling tactic.
Syria rejects any ‘‘incomplete’’ report that does not include investigations of sites where Syrian soldiers were exposed to toxic gases, said Foreign Minister Walid al-Moualem.
Syria’s official news media said the government would counter any US assault, noting vows by Iran to retaliate against a strike and statements of support from Venezuelan, Nicaraguan, and Czech officials.
Putin said he was sure the attack was the work of rebels trying to provoke international — and especially American — involvement in the Syrian conflict. The government of Bashar Assad, he said, would have had no reason to use chemical weapons at a time when it had gained the upper hand in the fighting.
Doing so, he said, would have been ‘‘utter nonsense’’ — with the clear implication that that is how he would characterize the American allegations. On top of that, he said, the Obama administration’s ‘‘claims that proof exists, but is classified and cannot be presented to anybody, are below criticism. This is plain disrespect for their partners.’’
Obama arrives in St. Petersburg for the G-20 meeting Thursday and leaves Friday. The purpose of the summit is to discuss economic growth, but the White House admits there will be plenty of talk about Syria on the side. There are currently no plans for a one-on-one meeting between Putin and Obama, who in early August decided not to attend a Moscow summit with the Russian president.