Condoleezza Rice, the US secretary of state, and Tony Blair, the Quartet's representative to the Middle East, said that the removal of Israeli roadblocks in the West Bank was critical to economic development in the area.
Rice said: "It's very difficult to do this in a kind of macro way, or a general way.
"It comes down to very specific issues, that issue of that checkpoint or that roadblock that's preventing that kind of economic activity in that town ... it gets that specific."
She also said that there was now "quite a bit of detail" on what effect the removal of 50 roadblocks that Israel had promised to remove would have.
"It's a much more labour-intensive and specific process than I think one could imagine," she said.
Blair told Al Jazeera that the key thing about the checkpoints was not their number but their strategic position.
He said that a lot of the checkpoints could be removed without hurting Israeli security and that this would allow a lot more economic activity to take place.
The UN says there are more than 500 obstacles impeding movement in the West Bank, including gates, checkpoints and dirt mounds blocking passages.Road map 'failures'
Salam Fayyad, the Palestinian prime minister, said that Israel's failure to address the settlement issue was one of the factors that had pushed peace talks towards collapse.
"Israel has failed to meet any of its obligations from the road map, including a freeze in settlement activity," he said.
"That is most troubling. Unless that changes, the political process is being stripped of its meaning."
After meeting Tzipi Livni, the Israeli foreign minister, Fayyad said that the Palestinian government had met its commitments by reforming its financial sector and praised the donor community for providing additional money.
However, Israeli officials noted that Livni had discussed with Fayyad the 60 road blocks, one major checkpoint, and other impediments to Palestinian freedom of movement that had been removed.
They also said that an additional 5,000 work permits had been granted to help Palestinians seeking work inside Israel.
A Paris donor meeting last year netted $7.7bn in aid pledges to the Palestinians over three years. The money was aimed for the Palestinian budget, as well as reform and development programmes.
|"Israel has failed to meet any of its obligations from the road map, including a freeze in settlement activity"|
Salam Fayyad, Palestinian prime minister
Rice said Arab countries that have pledged money to the Palestinian Authority, but not delivered, had been prodded to come up with the funding they have promised.
Mark Seddon, Al Jazeera's correspondent in London, said: "The only thing that is keeping Gaza going is direct payments to the Palestinian Authority.
"Some of this has come through but a lot of it is still needed. This is money that is essentially needed to run the Palestinian Authority itself.
"The good news from today is that Kuwait has said that money earmarked for development in Palestine is now going to go straight to the authority.
"The Palestinian prime minister has been busy telling everybody here how his reform packages have made everything more transparent and that people should be happier about giving money."
Before the London talks, aid agencies had urged the Quartet to use the meeting to press Israel to end its blockade of Gaza.
The group was told of the impending impending humanitarian crisis there and the difficulty of life for ordinary people.
However, speaking to Al Jazeera, Blair insisted that it was down to the Hamas movement, which took full control of the Gaza Strip last year, to renounce violence before help could be given.
"Everybody's got a big decision to make over the next few months. But I think Hamas have got a big decision as well," he said.
"The fact is you could change the situation in Gaza in my view. You could have a situation where the violence stops, the terrorism stops being visited out from Gaza onto the Israelis. The retaliation and violence stops from Israel into Gaza.
"And you get then a progressive lifting of the bloackade, the crossings can be re-opened, normality can return. And I think for people in Hamas this is a very big decision they are going to have to make."