Tony Blair today warned that the Middle East peace process remained "a fragile enterprise" despite recent progress.
But the Prime Minister said moving the process forward would help not only the people of the region but enhance the security of nations across the world.
His comments came in his opening remarks to the London meeting he was hosting today designed to find ways in which the international community can support the Palestinian Authority in setting up proper structures of government and security.
Palestinian president Mahmoud Abbas, United Nations Secretary General Kofi Annan, US Secretary of State Condoleezza Rice and representatives from the World Bank and the IMF were among the delegates from 23 nations and six institutions attending the meeting at London's QE2 Conference Centre.
Mr Blair told them: "The significance of this issue and the Middle East peace process - or frankly lack of it over the past few years - is not confined to Israel, Palestine or even to the Middle East. It's something that concerns all the countries represented here today.
"There's probably no more pressing political challenge than to move this process forward because it has a relevance on the streets of Britain, on the streets of European countries as well as in the Middle East itself.
"It's probably the cause most used or abused," by extremists across the world.
The Prime Minister went on: "When we therefore make progress on this issue we are not simply enhancing the prospects of the people of Palestine we are also enhancing the security of everyone of the countries represented here today."
He said terrorist groups were still trying to disrupt the process, as they did last Friday with the Tel Aviv suicide bomb.
The Prime Minister said the terrorists' aim was to "de-rail this process, to stop it".
He went on: "That's why it's so important that our response to them is to say we won't be stopped from making progress - on the contrary we will redouble our efforts."
Mr Blair said there had been hopeful signs recently but went on: "All of us know that despite these good signals of progress this is still a fragile enterprise that can so easily be set back as it has been set back on other occasions."
The Prime Minister said the purpose of today's meeting was to see how the Palestinian Authority could be helped to establish a viable state with good governance, proper security and a secure economy.
He praised Mr Abbas for having produced "clear plans for the Palestinian state of the future".
Mr Blair added: "What we need to say, is how do we help and support that?"
He stressed donor countries wanted to see that any support they gave was being used to better the lives of the Palestinian people.
The Prime Minister told delegates: "This is a moment of opportunity. It's vital that we seize it. I am confident that we can. But the one thing we have learned over the past few years is that the peace process never happens just because of expressions of goodwill, there has to be a hard slog in the detail, in the day-to-day management, to get it done and I hope today's conference can provide some specifics to that goodwill and solidarity."
Mr Abbas, in his opening remarks, said he had no doubt whatsoever about supporting the conference.
He went on: "This conference addresses our needs to find a stable atmosphere to open political paths to put an end to violence and counter-violence.
"This cycle only leads to more complexities and hinders the peace process.
"For us as Palestinians we are going forward to put our house in order and to address our commitments as in the peace process, as in the Road Map. We only have one demand and that is reciprocity according to the Road Map."
Mr Blair has said he hopes today's meeting, coupled with Israeli Premier Ariel Sharon's plans for withdrawal from the Gaza Strip and some of the West Bank can lead to negotiations under President George Bush's Road Map to be reopened.
Mr Abbas said he believed good progress had been made during his brief period of office towards establishing proper democratic structures in the Palestinian authority.
"We have demonstrated our democratic values and our democratic behaviour," he said.
He promised a Palestinian state would be based on the rule of law and "institutions governed by modern rules and an independent judiciary".
The meeting continues for the rest of the day, with Mr Blair due to host a closing press conference this afternoon.
Mr Annan told the meeting he wanted to express "full and strong support for the reform effort of the Palestinian authorities".
He said Mr Blair was to be "warmly congratulated for his timely initiative".
And he went on: "This is a moment of promise and potential, the sense of expectation is palpable ... the prevailing mood is one of optimism."