MOSCOW/WASHINGTON: Russia on Friday called the deployment of US troops in Jordan over the Syria crisis an unconstructive step that threatens to expand the conflict.

US Defence Secretary Chuck Hagel revealed on Wednesday that 150 US military specialists had been deployed in Jordan since last year and that he had ordered the army to bolster the mission by bringing the total American presence to more than 200 troops.

Russian foreign ministry spokesman Alexander Lukashevich said such a move ran counter to internationally-agreed principles for ending the crisis through negotiations.

“These are absolutely not the actions that we now need to bring Syria out of its dead end,” Lukashevich told reporters.

“These actions exacerbate the Syria crisis, which is now gaining the dimensions of a regional crisis,” the spokesman said.

Russia is viewed as one of Syrian President Bashar al-Assad’s few allies because it vetoed three rounds of UN Security Council sanctions against his government.

Meanwhile, US intelligence agencies are investigating accounts from European allies that Syria may have used chemical weapons in its war against opposition forces, a senior US official said Thursday.

There were indications a “deeply suspicious” agent may have been used in recent battles in Syria but spy services were still evaluating the information and had not reached a definitive conclusion, the official told AFP on condition of anonymity.

Chemical weapons may have been used in a limited, “localized” way and not on a large scale, the official said. Diplomats had told reporters earlier this month that Western countries had “hard evidence” that chemical weapons had been used sporadically in Syria.

Britain and France have presented information to the United Nations on allegations that Syrian regime forces fired chemical arms in the city of Homs in December and at Ataybah near Damascus last month.

The Washington Post and Foreign Policy reported that London and Paris had informed UN Secretary-General Ban Ki-moon that soil samples, witness interviews and other information showed nerve agents were used in and around Aleppo, Homs and possibly Damascus. The US official said the accounts from France and Britain were being taken seriously.

But other officials and analysts said intelligence agencies faced a difficult challenge trying to confirm the reports given the chaotic, violent conditions in Syria and a dearth of American spies in the field.

“The intelligence community has not verified the use of chemical weapons in Syria,” said a second US official, who also asked not be named. President Barack Obama has warned Damascus that the use of chemical weapons would constitute a “red line,” implying but not explicitly threatening possible US military action.

If the allegations are confirmed, Obama—who has sought to avoid any US military role in the civil war—would face increased pressure to intervene. The Obama administration has never precisely defined exactly what would constitute crossing the rubicon when it comes to chemical weapons in Syria.