Britain pledged to increase support for Syrian opposition forces on Friday as William Hague warned the resignation of peace envoy Kofi Annan was a "bleak moment" in efforts to end the bloodshed.
The Foreign Secretary insisted the diplomatic approach was not dead and defended the UK's efforts to secure international agreement, but accepted "other things" also needed to be done.
"Given the scale of death and suffering and the failure so far of the diplomatic process we will, over the coming weeks, increase our practical but non-lethal support," he told BBC Radio 4's Today programme. "It will not involve sending armaments."
Hague declined to comment on any potential involvement of UK intelligence, saying " I can say that we are helping elements of the Syrian opposition, but in a practical and non-lethal way.
"We have helped them with communications and matters of that kind, and we will help them more."
According to activists in Syria 170 people died across the country on Thursday as the government continued its assault on Syria's biggest city, Aleppo.
Rami Hamwi, a witness to the violence in Syria's fourth largest city, Hama, told Avaaz: "At 5am this morning, I woke up to see huge military reinforcements camped at the eastern end of Aleppo Road. Clashes started there between FSA and regime forces, and became especially fierce when regime forces surrounded Arbeen neighbourhood."
Another activist living in the city, Mou’ayad Hamwi told Avaaz they were trapped: “We cannot flee the neighbourhood - the shelling is violent and snipers are scattered on the rooftops of buildings that surround the neighbourhood. We are trapped in here, we will die either in our homes from the shelling or while trying to flee.”
Mr Annan cited "finger-pointing and name-calling" in the 15-nation UN Security Council as one of the reasons for his decision to step down.
Russia and China have blocked British-backed resolutions in the Security Council to threaten the Assad regime with global sanctions if it fails to halt the bloodshed in the 17-month uprising.
There was little sign of progress on the issue in Downing Street talks between Prime Minister David Cameron and Russian President Vladimir Putin on Thursday.
Mr Cameron urged the UN to "ramp up" pressure on the regime of Syrian President Bashar Assad and said that Mr Annan's resignation showed his plan for a ceasefire to pave the way for talks on a political settlement had not worked.
Mr Hague said his departure should not, however, halt efforts to secure agreement.
He added: "It is not dead but you are quite right to say it is a bleak moment not only for the people of Syria but for our diplomatic efforts. Diplomacy has so far failed the people of Syria.
"We do not give up on the diplomacy with Russia and with China; we will keep going with that as long as this situation continues but we will have to do other things as well."
He denied the UK was among those who had failed Mr Annan.
Mr Hague said: "We have really been trying to give him the backing he needs and have often bent over backwards to reach agreement with Russia and China on this.
"Do we disagree with Russia and China? Yes, on this point...that we believe it is not only necessary to press for the plan that Kofi Annan put forward - and it will continue to be necessary even without Kofi Annan to do that - but that the Security Council needs to back that up with the threat of consequences."
The 193-member UN General Assembly is expected to approve a resolution today denouncing the use of major military hardware against opposition forces and demanding chemical and biological weapons not be deployed.
But the text tabled by Saudi Arabia has been stripped of calls for the resignation of Mr Assad and for wider sanctions amid pressure from countries such as Russia, which said it was "unbalanced".