President François Hollande came under pressure yesterday to follow Barack Obama and David Cameron and allow a French parliamentary vote on punitive air strikes on Syria.

The Assemblée Nationale (lower house) will debate the alleged use of poison gas by the Syrian regime on Wednesday but no vote is planned. According to one interpretation of the French constitution, a parliamentary vote on military action is impossible until four months after the President of the Republic decides to act.

President Obama’s decision to delay military strikes and seek Congressional approval has, however, caused a potential domestic crisis for President Hollande. Several senior opposition figures yesterday backed away from or directly criticised the planned French participation in US air raids on Syria. They called on the government to put the intervention to a vote on Wednesday.

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Jean-Francois Copé, leader of the main centre-right party, who had previously supported Mr Hllande, said no raids should happen until UN inspectors had reported. The first secretary of Mr Hollande’s Socialist party, Harlem Desir, accused him of adopting the “Munich-like” approach of French politicians who appeased Nazism in the 1930s.

However, dissenting voices can also be found in the centre, the far right, the hard left and within Mr Hollande’s Socalist ranks. Opinion polls suggest that popular opposition is growing and stands at around 64 per cent.

The interior minister, Manuel Valls, said yesterday that there was no question of France going it alone in air strikes on Syria if the US Congress voted against. “We need a coalition,” he said.

Opposition figures pointed out that this had put Mr Hollande in the “humiliating” position of having to wait for a US parliamentary vote before sending in the French military while refusing to allow a vote in France.

Mr Hollande had expected the air raids – including a substantial contribution by |France – to occur before Wednesday’s parliamentary debate in Paris. President Obama called him to say that he was postponing the strikes and seeking Congressional approval just before his announcement in the White House rose garden on Saturday.

The French government is expected to release today a four page synthesis of its own intelligence reports pointing to the responsibility of the Assad regime in the gas attacks on a Damascus suburb on 21 August. In an attempt to defuse the calls for a vote on Wednesday, the Prime Minister, Jean-Marc Ayrault, has also called principal opposition leaders and the heads of the national assembly senate defence and foreign affair committees to a briefing this evening.

The interior minister, Mr Valls, said the calls for a vote on Wednesday were unconstitutional. He pointed out that the wording of the Fifth Republic constitution stipulates that the President must “inform” parliament within three days of military action. The constitution goes on to say that a debate “can occur but it will not be followed by a vote.”

Parliamentary approval is need only if the fighting continues for more than four months.

Mr Valls said the French constitution could not be “altered according to daily events”. He said Mr Hollande’s determination to act was “intact”. The “worst thing would be to do nothing…the face of a crime against humanity,” he said.

Defence sources say that that the French share in any attack would not be just symbolic or passive. France does not have Tomahawk cruise missile but it does have modern weapons which would allow it to attack selected targets in western Syria without sending its aircraft into heavily-defended airspace.

The sources said that France would probably deploy Rafale fighter-bombers from bases in France or Djibouti. These aircraft carry SCALP-EH high-precision missiles which can be fired from 300 kilometres (almost 200 miles) away.