Hamas has set new terms for implementing a reconciliation deal with Palestinian President Mahmoud Abbas's rival Fatah group, an official said on Thursday, dimming even further chances the accord will be put into effect.

Abbas and Khaled Meshaal, Hamas's political chief in exile, agreed in Qatar this month to form a unity government led by the Western-backed president but a Fatah official said after talks in Cairo divisions within Hamas were holding up progress.

The internal splits within Hamas have cast a shadow on the meetings and Hamas is not able to implement the agreement signed in Doha. Its leaders have asked to delay discussions on forming the government, said the official who declined to be named.

Soon after the Doha agreement was signed the Islamist group's leadership outside the Gaza Strip was criticised by those inside the Hamas-ruled enclave, particularly the deal's call for Abbas to serve as prime minister as well as president.

At an internal meeting chaired by Meshaal in Cairo on Wednesday, Hamas officials united behind new demands, said a Palestinian official involved in the talks. The terms seemed certain to be rejected by Abbas.

Hamas demanded to keep the key ministries in the new government, including the ministry of interior, said the official. It also demanded no change in the structure of security services in the Gaza Strip.

The interior ministry oversees the Hamas-run security services, and Palestinian political analyst Samir Awad said the new terms proved the group was not prepared to abandon control of Gaza, territory it seized from Fatah in fighting in 2007.

Abbas has been seeking a unity government staffed by independents and technocrats to ensure it would not be boycotted by the West, which donates essential funds to his Palestinian Authority and refuses to deal with Hamas over it hostility toward Israel.

Other demands that emerged from the Cairo meeting included naming a Gaza-based deputy to Abbas and making his appointment as prime minister conditional on a vote of confidence in the Palestinian parliament.

The legislature has not been in session since the collapse five years ago of a short-lived Palestinian unity government.

(Additional reporting by Ali Sawafta in Ramallah, Editing by Jeffrey Heller and Ori Lewis)