Officials in Britain and the United States are reportedly investigating new claims that Syrian President Bashar Assad used chemical weapons, less than a year after Damascus staved off Western military intervention by vowing to destroy its chemical arms stockpile.

British officials told the London Times they were looking for more information regarding four alleged attacks around Damascus from January to April. The paper also reported that US and Turkish officials were looking into the claim that chlorine and pesticides were used against the opposition.

The report comes several days after a senior Israeli defense official accused Assad’s regime of using chemical weapons in two attacks near Damascus in late March.

The official claimed that two attacks were carried out on March 27 in the Harasta neighborhood of Damascus, and that the effects of the chemicals lasted for several hours.

He said that nonlethal agents were used to incapacitate opposition fighters.

According to the official, the compound used in the attacks was not listed among the chemicals that Syria committed to dispose of when it signed an agreement in September 2013 to give up its chemical weapons.

Opposition sources claimed three people were killed in the Harasta attack.

The Times reported that alleged attacks in Daraya, Adra and Jobar were also being investigated. It said that soil and clothing samples from attack sites had been given to authorities in Jordan and Turkey.

After the Jobar attack, a video posted to social media by opposition groups appeared to show a man suffering respiratory distress and other symptoms consistent with a chemical attack.

The Assad regime had vowed to rid itself of chemical weapons after a devastating attack in August on the Damascus suburb of Ghouta killed over 1,000 people. The attack drew widespread condemnation and threats of military action by the US, Britain and France.

On Thursday, an official at the chemical watchdog overseeing the removal of the stockpile said an ambitious June 30 deadline for destroying the country’s chemical arms could be met if Syria manages to remove the ingredients for poison gas and nerve agents from the country.

It remains to be seen if Damascus can ship out the chemicals by the end of April. It has taken months to transfer just over half of the 1,300-metric ton stockpile. Overland shipments through the civil war-torn country to the port of Latakia are only happening sporadically.

Under a timeline drawn up last year, the most toxic chemicals were to have been removed from the country by December 31, 2013, but that deadline was missed due to poor security and other factors. Syria later submitted a new timeline.

“Right now we have got 17 days left according to the timetable that the Syrian government gave to the OPCW with which they committed to remove their chemical weapons,” said Michael Luhan of the Organization for the Prohibition of Chemical Weapons. “So if they are out at that time, we are confident that the destruction activity can be completed in time to meet the June 30 deadline of the mission.”