The French government has published an intelligence dossier that it says shows the forces of the Syrian president, Bashar al-Assad, carried out a "massive and co-ordinated" chemical attack that is believed to have killed hundreds of people.

A nine-page document, published at around 7pm French time on Monday, stated the information had come from "France's own sources" and was based on a detailed technical analysis of evidence supplemented by "additional elements gathered in co-operation with our principal partners".

It was reportedly shown to French ministers and heads of parliamentary groups during an emergency meeting on Syria at the offices of the prime minister, Jean-Marc Ayrault, at Matignon early on Monday evening.

The report and a video, drafted by French intelligence services, purports to show that forces loyal to Assad were responsible for the chemical attack that came from east and west Damascus and targeted rebel-held zones on 21 August, a source told Reuters.

On Monday, Ayrault summoned the defence and foreign affairs ministers, the heads of the Assemblée Nationale and the upper house, the Sénat, as well as the heads of various parliamentary groups and commissions, to present the "proof" before a parliamentary debate on Wednesday.

Before the meeting Ayrault had promised "total transparency" on the situation in Syria and evidence that the regime in Damascus had used chemical weapons, reportedly sarin, against its own people.

Ayrault was reported to have handed over "declassified" documents to those gathered that "clearly identify" that Assad's regime was responsible for the attack.

The Assad regime denies this. It blames rebel forces for using the chemical bombs.

The document states: "Syria has one of the most important operational stocks of chemical weapons as part of an old and diversified programme that has been the subject of surveillance by the French [intelligence] services, and those of our principle partners, for a long time. This programme is one of the primary threats in terms of the proliferation of arms of massive destruction …

"In its battles engaged against the opposition to the regime of President Assad, Damascus has already employed such arms, namely sarin, in limited attacks against its own population, particularly in April 2013.

"The analysis of information that we have today leads us to believe that on 21 August 2013 the Syrian regime launched an attack on certain areas of the Damascus suburbs held by opposition units, using a combination of conventional weapons and the massive use of chemical weapons."

The report details the Syrian chemical weapons programme, which it says began in the 1970s with the importing of chemical weapons. It states that Damascus has more than 1,000 tonnes of chemical agents making it "one of the most important operational stocks in the world". It describes Syria's chemical arsenal as "particularly massive and diverse", including Yperite, VX (one of the most toxic chemical agents known) and "several hundred tonnes of sarin".

"The sarin and the VX … are partly stocked in a binary form, that is to say kept in the form of two chemical products called precursors, that are mixed just before use. This technique and the associated procedures show a great knowledge of the technology of chemical weapons by the Syrian regime."

The report continues: "Damascus is capable of delivering its chemical weapons with a very large range of several thousand vectors." These, it says, include Scud C, Scud B, M500 missiles, bombs and artillery rockets with a range of up to 500km.

"Certain missiles can carry up to several hundred litres of toxic agent."

It adds that intelligence reports suggest the Syrians are looking at new ways of dispersing chemical weapons.

"Notably, since the beginning of the conflict, our intelligence confirms the regime's use of munitions carrying smaller amounts of chemical agents adapted for tactical use as they are more accurate and localised.

"We cannot rule out that these trials have also been conducted using other types of chemicals normally meant for civil use and employed at a lethal dose."

Under the heading: "The chain of command and the responsibilities", the report says the Syrian Centre for Scientific Research Study (CERS) is responsible for producing toxic agents for use in war, pinpointing "Branch 450" as being responsible for filling munitions with chemicals and also the security of sites where the chemical agents are stocked. This branch, it claims, is "composed only of Alawite military personnel … distinguished by a high level of loyalty to the regime".

"Bashar al-Assad and certain influential members of his clan are the only ones permitted to give the order for the use of chemical weapons. The order is then transmitted to those responsible at the competent branches of the CERS. At the same time, the army chiefs of staff receive the order and decide on targets, the weapons and the toxic agents to put in them," it states.

The French report claims the Syrian regime has used chemical weapons against areas held by opposition forces "with the aim of taking territory or causing terror" for several months.

"The competent French services have recuperated biomedical samples (blood, urine), environmental samples (earth) and materials (munitions) taken from victims or sites of attacks on Saraqeb, on 29 April 2013, and Jobar, in mid April 2013. The analysis carried out confirms the use of sarin."

The document's publication is aimed at swaying public opinion. While France, along with the United States, is pushing for military action against the Assad regime, a poll at the weekend showed that 64% of French people were opposed to a military intervention.

After the United Nations sent in an inspection team to verify the claims and counter-claims, Anders Fogh Rasmussen, the Nato secretary general, said he was personally convinced that Assad was responsible for the attacks.

The former French prime minister Alain Juppé told French journalists France could not act alone, but must act. He said: "To do nothing would be a dishonour for democracy. On the other side, to act is a very big risk given the international context."