Moscow (Russia) (AFP) - Russian Foreign Minister Sergei Lavrov on Friday said Moscow had "irrefutable" evidence that an alleged chemical weapons attack in Syria was staged with the help of a foreign secret service.

"We have irrefutable evidence that this was another staged event, and that the secret services of a certain state that is now at the forefront of a Russophobic campaign was involved in this staged event," he said during a press conference.

According to Syrian medics and a statement by the World Health Organisation, more than 40 people died in an April 7 strike on the former rebel outpost of Douma of symptoms consistent with the use of chemical weapons.

The US and its allies believe the Syrian regime was behind the attack, but Russia has long insisted it was staged by rebels in an attempt to provoke further Western intervention.