ANKARA: Militant opposition fighters in northern Syria are preparing a “staged” chemical gas attack, Russia claimed on Saturday, amid growing speculation that an Assad regime assault on Idlib province is imminent.

Moscow’s accusation comes after US President Donald Trump’s national security adviser John Bolton this week said Washington will respond “very strongly” if Syrian President Bashar Assad uses chemical weapons in an offensive to retake Idlib, one of the last rebel held provinces in the country.

Russian defense ministry spokesman Igor Konashenkov said in a statement that the extremist group Hayat Tahrir Al-Sham is “preparing another provocation of the ‘use of chemical weapons’ by Syrian government forces against the peaceful population of the Idlib province.”

He said the group delivered “eight chlorine tanks” to Jisr Al-Shughur town in order to “stage” the attack and that these were later taken to a village eight kilometers (5 miles) away.

The statement also said a group of militants “trained in handling poisonous substances under the supervision of specialists from the private British military company ‘Oliva’” arrived in the town a day earlier.

“The militants have the task of simulating the rescue of the victims of the chemical weapons attack dressed in the clothes of the famous ‘White Helmets’,” it said.

Konashenkov accused British special services of being “actively involved” in the “provocation” which will “serve as another reason for the US, the UK and France to hit Syrian government targets with air strikes.”

In April, the US, France and Britain launched joint missile strikes on Syrian targets in April in response to regime chemical weapons attack on the town of Douma.

Russia and Syria claimed at the time that the Douma attack had been staged by the opposition. Now the militant group Hayat Tahrir Al-Sham is “preparing another provocation of the ‘use of chemical weapons’ by Syrian regime forces against the peaceful population of Idlib province,” Russian Defense Ministry spokesman Igor Konashenkov said on Saturday.

Russia’s Deputy Foreign Minister Sergei Ryabkov warned the US against making any “reckless” moves in Syria. “We are hearing ultimatums from Washington ... and it does not affect our determination to continue our policy for the total elimination of terrorist epicenters in Syria and the return of this country to a normal life.”

Russia presented proposals last week to Turkish authorities on resolving the situation in Idlib, the last opposition-held stronghold, and talks between Ankara and Moscow have intensified in the past two weeks. 

Experts say Ankara is trying to prevent a regime assault on Idlib, and if it cannot be prevented, Turkey’s objective will be to prevent the targeting of moderate opposition groups and civilians.

Turkey, which hosts more than 3 million Syrian refugees, has sounded alarm bells over a potential influx from the province, where about 3.5 million civilians live. The intensified diplomatic traffic between Moscow and Ankara is feeding speculation about a Russian-supported assault by the Syrian regime on Idlib in the near term.

In Jerusalem on Wednesday, Bolton said Washington was “concerned about the possibility that Assad may use chemical weapons again.”

“Just so there’s no confusion here, if the Syrian regime uses chemical weapons we will respond very strongly and they really ought to think about this a long time,” Bolton said.

Speculation is increasing that there could be a Russian-backed government assault on Idlib, one of the so-called “de-escalation” zones set up as a result of talks by Russia, Turkey and Iran last year.

On a visit to Moscow on Friday, Turkish Foreign Minister Mevlut Cavusoglu warned Russia that seeking a military solution in Idlib would be a “catastrophe” before meeting President Vladimir Putin.

Russian Foreign Minister Sergei Lavrov said the situation in Idlib is “multi-faceted” and called for separating out “the healthy opposition from terrorist structures.”

Damascus still holds the southeastern tip of Idlib, a strategically important province adjacent to Latakia on the Mediterranean coast that is home to Assad’s clan.

More than 350,000 people have been killed and millions displaced since Syria’s war started in 2011 with the brutal repression of anti-government protests.