The official said the European Union and other institutions and countries were considering financial support for Egypt in addition to a $4.8 billion loan which Cairo has requested from the International Monetary Fund (IMF).
"...Egypt will need more than this almost $5 billion, probably Egypt will need more than double this amount, more than $10 billion," the official told a briefing ahead of a visit to Brussels by Egyptian President Mohamed Mursi on Thursday.
The EU will "reinforce" the IMF package with aid of its own for Egypt, but was still considering how much support it would provide, the official said.
Egypt, which needs help to stave off a balance of payments crisis and rebuild confidence among investors who fled during 18 months of political turmoil, hopes to reach a deal with the IMF by the end off the year, officials in Cairo have said.
Mursi, on his first visit to Europe since he became Egypt's first freely elected president in June, will meet European Commission President Jose Manuel Barroso, foreign policy chief Catherine Ashton and Herman van Rompuy, president of the council of EU governments.
The meetings will take place two days after Tuesday's attacks on the U.S. embassy in Cairo, where protesters scaled the walls, tore down the U.S. flag and burned it. Demonstrators said they were protesting about what they said was a U.S. film insulting the Prophet Mohammad.
Later on Tuesday, protesters in Libya attacked the U.S consulate in Benghazi, killing the US ambassador and three other embassy staff.
The talks in Brussels are expected to cover economic support, job creation, agriculture, energy and European investment in Egypt, the official said. The Egyptians are focusing on developing the country's gas industry and renewable energy.
Trade will be on the agenda but the European Union is not yet ready to open talks with Egypt on a free trade agreement, the official said.
Egypt's future is important for the 27-member bloc, which sees the development of Arab Spring countries as an economic opportunity, but also fears the possibility of anti European governments on the other side of the Mediterranean.
Last year, the European Union introduced a "more for more" policy under which it links economic aid to progress in civil rights and democracy.