The UK will announce a "major" new donation in an effort to ease the humanitarian crisis in Syria but William Hague has rejected fresh calls from senior MPs to supply arms to help rebels withstand the onslaught of Bashar Assad's forces.
The Foreign Secretary told the Commons that the UK would reveal the aid contribution at an international conference later this week and also announced the deployment of a Royal Navy warship to safeguard chemical weapons stocks being removed from Syria for destruction.
Faced with demands to provide weapons to the Free Syrian Army Mr Hague said he was not proposing such a move but said supplies of non-lethal equipment, which have been suspended amid fears equipment could end up in the hands of extremists, could be resumed and increased if the security situation improved.
Mr Hague's comments came as I nternational Development Secretary Justine Greening warned that the failure of wealthy nations to meet promises of humanitarian aid were putting Syrian lives at risk.
Ms Greening appealed for "significant" extra help for the estimated nine million civilians affected by the fighting to be agreed at an international "pledging conference" on January 15.
Her alert that commitments had so far "fallen well short" came as the UK announced the allocation of the final part of the £500 million it has pledged so far.
The £30 million package will specifically target women and child refugees, including the provision of "safe spaces" in Syria and Iraq, food vouchers and health and sanitary funding.
The UK's contribution is the country's largest ever humanitarian response - and almost equals that given by the other 27 EU member states combined, officials say.
United Nations secretary general Ban Ki-moon is hosting the conference in Kuwait on Wednesday - a week before the scheduled start of peace talks in Geneva.
The latest UN aid appeal is its biggest ever at 6.5 billion US dollars (£3.95 billion) but existing pledges remain well short and undelivered despite warnings of dire consequences.
Mr Hague told MPs the UK "will make a major further donation in response to the new UN appeal ... and we will urge other countries to be equally generous".
But senior MPs warned that humanitarian assistance and non-lethal aid to the rebels including communications and logistical support would not help end the bloodshed.
Tory Richard Ottaway, the chairman of the Commons Foreign Affairs Select Committee, said: "If the people of Syria are to get their country back we should do all we can to support the moderate opposition in Syria and, if necessary, revisit the decision to supply only non-lethal weapons."
Mr Hague told him: "We are ready to resume and increase our support of important, but non-lethal, supplies, provided we are confident about what will happen to those supplies."
Tory former foreign secretary Sir Malcolm Rifkind said neither the UK nor the US had "any real clout on the Syrian moderate opposition because of our collective inability to provide them with any of the real material help they need in order to press home their objectives".
Alistair Burt, who was the Foreign Office minister responsible for the Middle East until losing his job in last year's reshuffle, asked how the "imbalance" between the forces loyal to Assad and the opposition Free Syrian Army could be addressed.
"If that is not to be addressed by the Geneva process, how can some balance be made that will give the regime an incentive to negotiate as opposed to feeling its position is particularly strong with the balance of forces as they are at present?"
It remains unclear whether the Western-backed Syrian opposition group will attend the so-called Geneva II talks in Switzerland next week.
Mr Hague and US secretary of state John Kerry were among foreign ministers from the Friends of Syria group who used weekend talks in Paris to try to persuade them to attend.
Internal disagreements within the increasingly-fragile Syrian National Coalition over whether to negotiate with president Assad threaten the diplomatic initiative.
Mr Hague said: "If the opposition go to Geneva II and the regime is not prepared to work on the basis of creating a transitional governing body drawn from regime and opposition, then many people across the world will draw the conclusion that they should be giving increased support to that moderate opposition in the face of diplomatic blocking from the Assad regime."
But in response to Tory former Cabinet minister John Redwood, who said as the security of non-lethal supplies could not be guaranteed it would be "unwise and foolish" for the UK to supply arms, Mr Hague said there was no plan for Britain to send guns to the rebels.
"I'm not proposing lethal supplies and I've always been very clear that we would come to this House and have a vote in this House if we were going to do that," he said.
Royal Navy frigate HMS Montrose will join Danish and Norwegian vessels transporting part of Assad's chemical weapons stockpile material as part of agreed international efforts to destroy them.
Britain will also provide specialist specialist equipment to help ensure the chemicals of the highest concern were "neutralised", Mr Hague said.
Labour pushed for Iran to be included in the peace talks but Mr Hague said Tehran needed to demonstrate it was committed to the Geneva process.
Shadow foreign secretary Douglas Alexander said while it was right to acknowledge the role Iran had played in "deepening and inflaming" the conflict, but its "claimed resolve to be part of the solution should be tested".
Mr Hague said: "There is no problem in principle in any quarter, certainly from Western nations, in Iran coming but there is a practical problem of 'are they prepared to play a constructive role if they get there. We would welcome stronger signals of that from the Iranians."
It is estimated that more than 125,000 people have been killed so far in the battle between government forces and opponents of the Assad regime.
Millions more have been forced to flee their homes and the UN has highlighted concerns that many left trapped amid the hostilities now face starvation.
Baroness Amos, the UN emergency relief coordinator said after visiting the capital Damascus: " The world must do more for all the people who are displaced.
"Many families are living in abandoned buildings, schools or in makeshift shelters, without enough food, clean water or medicine.
"We must help them to get through this very cold winter."
The Syrian regime and opposition forces were said by Russia and the US to both have agreed to consider the provision of safe passage for humanitarian aid to besieged areas.
Mr Kerry and Russian counterpart Sergei Lavrov revealed the prospect after talks in Paris which also centred on the prospects of a ceasefire and prisoner exchanges.