Former Foreign Secretary William Hague will answer questions in the House of Commons in place of the Prime Minister tomorrow, a spokesperson in David Cameron's office confirmed.
British firms probably supplied the chemicals that have been used to make the nerve agent sarin in Syria, according to Foreign Secretary William Hague.
In a written statement to MPs he said that between 1983 and 1986 a review of the records showed a number of companies exported substances but they had legitimate uses for producing plastics and pharmaceuticals and they were not restricted under UK or international law.
He added: "From the information we hold, we judge it likely that these chemical exports by UK companies were subsequently used by Syria in their programmes to produce nerve agents, including sarin.Some of the companies involved no longer exist."
A UK chemical trader may have sourced some of the substances in question rather than producing them in the UK, he wrote.
Hague said Britain was "playing its full part" in the international effort to eliminate Syria's programme and he expected a ship carrying chemicals to be destroyed will arrive from the country next week.
Foreign Secretary William Hague hailed an European Union agreement with Ukraine, Georgia and Moldova as a "great step forward for them and their democracies".
Congratulations to Ukraine, Georgia, Moldova on signing agreements with EU. A great step forward for them and their democracies
Foreign Secretary William Hague tweeted following his meeting with Kurdish Regional Government leaders in northern Iraq:
Foreign Secretary William Hague wrote on Twitter:
I welcome President Poroshenko's ceasefire plan in #Ukraine. Vital Russia gives visible support including stemming flow of arms
Barack Obama has discussed Iran having a role in helping to stabilise Iraq - so long as it respects all sides. The UK Foreign Secretary William Hague has already spoken about talking to Iran.
But Mr Hague told ITV News today there would be no on-the ground sharing of British counter-terrorist expertise with Iranian officials.
ITV News Political Editor Tom Bradby spoke to Mr Hague:
David Cameron has said it's important he doesn't "pick Iraq's leaders" during a meeting with Nato's General Secretary Anders Fogh Rasmussen at Downing Street.
Mr Cameron told waiting journalists: "It's important that I don't pick Iraq's leaders, the people of Iraq pick their leaders, but what matters is that those leaders run that country on a non-sectarian basis, because running it on a more sectarian basis is part of the problem we are facing today."
The meeting took place as president Barack Obama prepared to announce that he is deploying about 100 Green Berets to Iraq to help train and advise Iraqi forces.
William Hague has told ITV News that under the current circumstances, the Government is "not planning, contemplating, or having meetings about Britain taking military action in Iraq."
He said that moves are being made to try to persuade Iraqi leaders to work together, provide aid and expertise, but "none of that means British soldiers going to Iraq".