The US should present the evidence it possesses of a chemical weapons attack by the Syrian regime to the UN Security Council, Russian President Vladimir Putin said on Saturday, amid rising tensions in the region ahead of a possible US-led military response in Syria.

“If they say that the [Syrian] governmental forces used weapons of mass destruction… and that they have proof of it, let them present it to the UN inspectors and the [UN] Security Council,” Putin said, speaking to journalists in Vladivostok.

“Claims that the proof exists, but is classified and cannot be presented to anybody are below criticism. This is plain disrespect for their partners,” he added.

Putin also called the allegations against the Assad regime “utter nonsense.”

“While the Syrian army is on the offensive, saying that it is the Syrian government that used chemical weapons is utter nonsense,” he said.

Addressing US President Barack Obama as a Nobel Peace Laureate, Putin urged him to think “twice before making a decision on an operation in Syria.”

Putin went on to praise the UK for its parliament vote rejecting participation in any military action against Syria, adding that the upcoming G-20 summit meeting in Saint-Petersburg on Sept 6 and 7 was a good platform to discuss the situation, the Voice of Russia reported.

Putin’s challenge to Washington to present its findings to the Security Council came hours after Obama said he was considering a “limited, narrow action” in Syria, and after US Secretary of State John Kerry warned of “guaranteed Russian obstructionism of any action through the UN Security Council.”

In a State Department speech Friday night, Kerry outlined the evidence the US possesses of the August 21 attack, which the US says killed 1,429 people.

Obama said the United States has an obligation “as a leader in the world” to hold countries accountable if they violate international norms on use of chemical weapons.

On Friday, a Russian Foreign Ministry official called Washington’s “threats” of a strike on Syria unacceptable and urged the US to wait for the results of the investigation of the UN chemical weapons inspectors who left Syria early Saturday.

The Syrian government has dismissed the US administration’s claims as “flagrant lies” akin to faulty Bush administration assertions before the Iraq invasion that Saddam Hussein had weapons of mass destruction. A Syrian Foreign Ministry statement read on state TV late Friday said that “under the pretext of protecting the Syrian people, they are making a case for an aggression that will kill hundreds of innocent Syrian civilians.”

In this undated file photo a Russian S-300 anti-aircraft missile system is on display in an undisclosed location in Russia (photo credit: AP)

In this undated file photo a Russian S-300 anti-aircraft missile system is on display in an undisclosed location in Russia (photo credit: AP)

Meanwhile, Russia has postponed the delivery of fighter jets and S-300 missile defense systems over a failed financial transaction, Ria Novosti reported on Saturday, citing a report in the Russian daily Kommersant.

Russia drew fire in June when reports of the sale gained mass media attention. The systems are considered to be the cutting edge in aircraft interception technology and would present a serious obstacle to any bombing of Syrian targets or the potential implementation of a no-fly zone.

In May, the US and Germany urged Russia not to deliver the systems, saying it would alter the balance of power in the Middle East and prolong the civil war

“We ask them again not to upset the balance within the region with respect to Israel,” Kerry said at the time. “The weaponry that is being provided Assad whether it is an old contract or not, has a profoundly negative impact on the balance of interests and the stability of the region and it does put Israel at risk. It is not in our judgment responsible because of the size of the weapons, the nature of the weapons and what it does to the region in terms of Israel’s security…”

Israel has indicated that it would attack the missiles if they are delivered.

In 2010, Russia had suspended the sale over Israeli and US objections.