Syria attack 'maybe' timed against EU conference

“Maybe it is not by chance that it is exactly when the international community, 70 different countries and organisations come together to try and build peace … Maybe it is not a chance that it is right in a moment like this that such attacks come,” she said.

The EU-sponsored conference, which takes place in Brussels on Wednesday, is designed to prepare for post-war state building in Syria.

Russia, which is fighting in Syria on behalf of Syrian president Bashar al-Assad, is in charge of separate talks on brokering a ceasefire.

It has said its ally should stay in power as part of Russia’s broader strategy to increase its influence in the Mediterranean, but the EU says Assad must go.

The Syrian regime and Russia denied firing the gas on Tuesday.

Mogherini also said she had no evidence of whose warplanes were involved. “As we gather here in these days on Syria, we share whatever we can share in terms of information,” she said.

British prime minister Theresa May called for an international investigation, but hinted that Assad was responsible.

“There can be no future for Assad in a stable Syria which is representative of all the Syrian people … We cannot allow this suffering to continue”, she said.

The attack took place in the town of Khan Sheikhun in north-east Syria, targeting refugees, including children, and medical staff, in an area controlled by pro-Western rebels.

It came after Syrian and Russian warplanes bombed civilians in rebel-held parts of the Syrian city of Aleppo.

Several EU states, including France, Germany, and the UK, have trained and equipped the rebels and launched their own air strikes in Syria in order to fight the jihadist group, ISIS.

Iran, Gulf Arab states, and Turkey are also fighting in Syria on different sides in a conflict that, Mogherini said, was unlikely to end soon.

“After seven years of war, you cannot expect one round of talks or two rounds of talks to bring the solution to everything … even such an important conference as the one we are having”, she said on Tuesday.

Russian leader Vladimir Putin has called on Western states to pay for Syria’s post-war reconstruction.

Mogherini said the EU would contribute because the amount of money needed would be more than Russia and the Syrian regime's other ally, Iran, could afford.

She indicated that the EU would not pay to rebuild Syria just for it to be ruled by Assad and Putin, however.

“We do not imagine in any possible way that there can be a situation where the European Union takes the bill regardless of any kind of political dynamic,” she said.