Syrian army soldiers have found chemical agents as they entered rebel tunnels in Damascus suburb of Jobar, Syrian TV reports, adding that some of them started suffocating.

Soldiers "entered the terrorists’ tunnels and saw chemical agents," state television quoted a "news source" as saying. "In some cases, soldiers started suffocating while entering Jobar," it said.

"Ambulances came to rescue the people who were suffocating," it added.

The source added that army troops were preparing to storm the suburb where rebels are believed to be based, Reuters reports.

Rebels fighting to oust President Bashar Assad accuse government forces of attacking people in the Damascus suburbs with toxic gas. At the same time, the ruling regime has dismissed the accusations.

However, some Western powers suspect Assad’s forces to be behind the attack that the opposition claims killed anywhere between ‘dozens’ to ‘1,300’.

France says that all indications show that Syrian army troops are responsible for what it called a "chemical massacre".

"All the information at our disposal converges to indicate that there was a chemical massacre near Damascus and that the Bashar regime is responsible," French Foreign Minister Laurent Fabius said on Saturday.

UK Foreign Secretary William Hague has suggested that "the Assad regime has something to hide" as the UN team, which is “20 minutes away” from the site of the recent attack, “have not been able to” go there and investigate.

“Why else have they not allowed the UN team to go there?” Hague said.

The White House said on Saturday that a ‘range of options’ is available on Syria if it’s proven that Assad’s forces used chemical weapons.

"We have a range of options available, and we are going to act very deliberately so that we're making decisions consistent with our national interest as well as our assessment of what can advance our objectives in Syria," the White House official said. "Once we ascertain the facts, the President will make an informed decision about how to respond," the official added.

President Obama is set to meet with his national security team later on in the day to discuss possible options.

In response, Iran has warned the US against possible military intervention in Syria, saying it will fuel tension across the region.

"Iran has announced several times that there is no military solution to the Syrian crisis, these provocative measures and moves make regional issues more complicated and fuel tensions," Iranian Foreign Ministry Spokesman Abbas Araqchi said. "The Syrian problem could be resolved only through a peaceful solution and there is no international permit for military meddling in Syria," he added.

UN High Representative for Disarmament Affairs, Angela Kane arrived in Syria to try to get access for the team of international inspectors to work at the site in the Damascus suburbs.

The US and European security sources have made a preliminary assessment that the Syrian government used chemical weapon, but still said they are seeking conclusive proof, which could take days, weeks or longer to gather.

On Saturday, UN High Representative for Disarmament Affairs, Angela Kane, arrived in Syria to try to get access for the team of international inspectors to work at the site in the Damascus suburbs.

On Wednesday a gas attack in Damascus suburbs was reported by opposition activists.

Next day the UN inspectors requested access to the site “without delays” on Thursday in order to investigate the alleged use of chemical weapons in attacks in the country.

The Syrian government said that it was ready to engage in “maximum” cooperation with UN experts, according to Russia’s foreign ministry.

On Friday the Syrian opposition said they will ensure the safety of UN chemical weapons experts as they pass through rebel-controlled areas, adding that their successful arrival at the site of an alleged gas attack near Damascus within 48 hours was ‘critical.’

The UN investigative team entered the country last Sunday. Three weeks ago an agreement was reached with Syrian President Bashar Assad’s government regarding the three different locations that were to be examined by the mission.  

• A Permanent Economic Emergency