Now that the unity accord has been signed, Hamas, its new friends in Fatah and a dozen other Palestinian factions must begin laying the groundwork for political reunification.

The first test facing the former enemies will be forming an interim government that the agreement says will be run by politically independent "technocrats".

They are supposed to govern the Hamas-controlled Gaza Strip and Fatah-run West Bank until there are national elections in a year or less.

So far, though, very little is known about how the interim administration would work or how its leaders will be chosen, raising speculation of a contentious selection process.

Samir Abdullah, a former politician familiar with the Cairo talks who works as an economist at Ramallah's Palestine Economic Policy Research Institute, said: "Saying that they want this technocratic government is not a very clear definition to start things.

"It's not certain how things will be done, if the process will be smooth, whether the groups will tolerate people not affiliated with them or people who have strong personalities and who have their own way of thinking."

Participants in the Cairo talks say the selection process has yet to begin because Mahmoud Abbas, the Palestinian Authority president and Fatah chairman, and his aides have been jockeying with Hamas for positions in the new government.

Even before Wednesday's signing ceremony, the two factions deliberately kept things vague, fearing that quarrels could have thwarted their pact, said Hani Masri, a Palestinian political analyst who has taken part in the reconciliation process.

"They were concentrating first and foremost on the success of signing the agreement," he said. That mindset seems not to have changed, with Mr Masri saying that "it's all manoeuvring now, nothing serious".

Palestinian officials have been taken by surprise by the speed at which the unity agreement was struck.

"Our people are still in Cairo, so we will see what we will do," said Nabil Amr, a member of the Palestine Liberation's Central Committee. The organisation, an umbrella group for Palestinian factions, including Fatah, is grappling with how to prepare for Hamas joining its ranks.

But what has become more apparent is the relative strength of Mr Abbas in his relationship with Hamas. While the Islamist group's prime minister, Ismail Haniyeh, who earned a popular mandate in the 2006 elections, is expected to step down, Mr Abbas will remain the Palestinian president until new elections are held.

The PA president also took a more prominent role during Wednesday's signing ceremony than Hamas' Damascus-based leader, Khaled Meshaal. He was forced to sit in the audience and delivered an address that, while perhaps more interesting, was noticeably shorter than Mr Abbas'.

This may have been a demand set by the Palestinian president to allay the concerns of Israel and the US, both of which consider Hamas a terrorist organisation. Israel, which has a history of negotiating with Mr Abbas, opposes the pact.

There is no question that Mr Abbas must remain president," said Talal Okal, a Gaza-based political analyst who was present at the ceremony. "There is no other solution - he will continue until elections."

Of all the factions signing up to the accord, Hamas is considered to have yielded the most. This, many believe, is partly a consequence of the group's increasingly precarious presence in Syria, as well the rising unpopularity of its rule in Gaza.

Mr Abbas now seems to be using this to leverage in his preferred choice for the interim government's prime minister, Salam Fayyad. Appointed by Mr Abbas in 2007 as PA prime minister, Mr Fayyad is disliked by Hamas, which says it prefers a prime minister from Gaza.

"When Hamas is asked about Salam Fayyad, their response is neither accepting nor refusing him," said Mr Masri. "I think the first week will be spent convincing Hamas to accept Fayyad".

Some of the names mentioned to succeed Mr Fayyad include Munib al Masri, the billionaire businessman who helped negotiate the agreement, and former Palestinian foreign minister Ziad Abu Amr.