Egypt urged rival Palestinian factions Fatah and Hamas to be serious and responsible in the Cairo-hosted comprehensive inter-Palestinian dialogue slated for Thursday, the BBC Arabic satellite TV reported on Tuesday.

"The main Palestinian factions should keep their responsibilities.... The Palestinians' interest lies in unity," said Hossam Zaki, Egyptian Foreign Ministry spokesman, adding that if the two groups undermine the Palestinian cause, the cost would be "unaffordable."

"Egypt's efforts would be fruitless if Palestinians do not defuse their feud," he said, referring to Hamas' boycott of a Cairo-hosted reconciliation dialogue in November.

Earlier on Tuesday, a Hamas delegation led by the group's exiled politburo deputy chief Moussa Abu Marzouk has arrived in Cairo for a preparative Fatah-Hamas meeting.

The delegation from Damascus would be joined by Ahmed Bahar, deputy speaker of the Hamas-dominated Palestinian Legislative Council based in Gaza.

Ahmed Bahar has said Tuesday at Egypt's Rafah border crossing that he was "optimistic" the unity dialogue would boost inter-Palestinian reconciliation and secure truce in the war-torn Gaza.

A fresh round of comprehensive inter-Palestinian dialogue, which involves all the Palestinian factions, organizations and other powers, will be held here on Thursday, the state MENA news agency reported Tuesday, quoting an anonymous high-level Egyptian official.

Meanwhile, Hamas spokesman Fawzi Barhoum said Tuesday that Fatah, which dominates the West Bank, and Hamas, which rules the Gaza Strip, will hold a preparative meeting on Wednesday to clear the atmosphere before the comprehensive dialogue among Palestinian factions.