A battle has commenced to save a celebrated children's charity, which is set to close in March 2008 unless it receives substantial government funding.

The London-based Kids Company has struggled to keep up with its annual running costs and is on the verge of closure.

The Archbishop of Canterbury, Dr Rowan Williams, is one of a host of key figures who have pledged support to keep the charity going.

In a speech at the charity's first conference next week , the Archbishop will call for a "strong and clear" message to be sent to the Government.

He will criticise current policies that are leaving a "very substantial percentage of our young people... at the side of the road as the rest of us go on".

In addition, the Church of England's most senior figure will say: "It has been said that you can gauge the moral temperature of a society by the way it treats its most vulnerable children.

"Are we as a society prepared to advocate for those who don't have voices of their own? And, above all, are we prepared to put the necessary resources, skills and commitment into the nurturing of our children?"

Reports last month stated that Kids Company would be forced to issue redundancy notices to staff at the end of October unless the Government commits itself to a long-term funding package.

Within days of that news being published, the Government contacted the charity and entered into discussions about increasing funding.

According to The Observer, senior government officials are to meet Camila Batmanghelidjh, founder of the charity, this week to find a unique funding package that could ensure long-term survival.

Batmanghelidjh said: "We present a new problem for the Government in terms of funding, because over 95 per cent of our children come to us directly off the streets instead of being referred via another charity or statutory organisation.

"This means there is no pot of money currently in existence that we can access. We are fighting to help children in a vacuum; in a dead care space."

Batmanghelidjh, who has re-mortgaged her own flat twice in efforts to keep the charity alive, was also the winner of the 2006 Woman of the Year award.

She said: "There does now seem to be goodwill in the Government and an inclination to breathe life into that dead space to help us continue to care for these children."

The charity's annual running costs stand at £4.5m, which Batmanghelidjh has had to try and raise from more than 4,700 different sources.

Talking about the struggle to find donors, Batmanghelidjh said: "For every one person I reach who agrees to donate money, four have turned me down."

The charity reaches out to 11,000 children each year that have suffered extreme abuse, violence and neglect. Fifteen independent evaluations have been made of the charity's effectiveness since 2000, and all have described it as "outstanding".

Dr Williams will give a keynote speech via video-link at Kids Company's conference.

According to The Guardian, he will say: "It seems that very often we're prepared to countenance the fact that a very substantial percentage of our young people are expendable. That they are to be left at the side of the road as the rest of us go on. That's not a vision that Kids Company has ever been prepared to settle with.

"I hope that there will be strong and clear words addressed to the Government, to statutory organisations, to civil society and to all of us as individuals, challenging us to think about what kind of skills, resources and faithfulness we owe to our children."