* Two liberal party sources say Brotherhood party leading
* Islamist al-Nour, liberal Egyptian Bloc also seen doing well
* Official results due later on Wednesday (Adds new Brotherhood statement, comments from other parties)
By Yasmine Saleh and Marwa Awad
CAIRO/ALEXANDRIA, Egypt, Nov 30 (Reuters) - The Muslim Brotherhood said on Wednesday it was leading in the initial count of results from the first round of Egypt's parliamentary election and one source in its party said it had secured 40 percent of votes cast for party lists.
A member of the rival liberal Egyptian Bloc also said that in Cairo, one area that voted on Monday and Tuesday, the list led by the Brotherhood's Freedom and Justice Party (FJP) had 40 to 50 percent of votes. His Bloc had 20 to 30 percent, he said.
Partial official results were due later on Wednesday but party representatives have been monitoring the count under way after the first stage of Egypt's first free election since army officers drove the king into exile in 1952.
The overall outcome will not be known until January. The election is spread over six weeks with different parts of the country voting separately in three phases, each of which may be followed by run-off votes. Under an elaborate system that makes it difficult to predict the outcome, two-thirds of the 498 elected seats go to party lists and the rest to individuals.
The FJP said in a statement early indications showed it in the lead for both party-list and individual mandate seats.
It said the ultra-conservative Islamist al-Nour party was next, followed by the liberal Egyptian Bloc.
An FJP source, who declined to be named, said it had secured 40 percent of votes cast for party lists across the nine governorates where voting was held in this week's first round.
The FJP statement said the party's strongest showing so far was in Fayoum, south of Cairo, followed by the Red Sea, Cairo and the southern city of Assiut. It said the rival Nour party was a strong competitor in Kafr el-Sheikh and Alexandria.
Other areas that voted in the first round include Luxor, Port Said and Damietta.
Basil Adel, whose party is part of the Egyptian Bloc, which includes liberal and other parties, said the bloc's list had secured 20 to 30 percent of votes counted so far in Cairo.
Adel, who is a member of the Free Egyptians party co-founded by Christian telecoms tycoon Naguib Sawiris, said the Brotherhood's list had secured 40 to 50 percent of the vote in Cairo, while Nour had 5 to 7 percent.
A source at another liberal party also said the FJP was ahead in the lists, but did not give numbers, while an official from another liberal group, the Justice Party, questioned the Brotherhood's claim to early success.
"All the numbers they came out with are presumptuous and are designed to create momentum for the second round," said Justice Party spokeswoman Nora Soliman, also without giving numbers.
Election officials said results would be given later on Wednesday for contests for individual seats, determining which candidates secured an outright win of more than 50 percent of the vote and which would need to go to run-off votes next week.
Results for party lists will not be announced until after the final round of voting finishes on Jan. 11.
The Brotherhood won 20 percent of seats in a parliament elected under Mubarak in 2005. That was its best showing and made it the strongest opposition bloc in an assembly dominated by Mubarak's now-defunct National Democratic Party (NDP).
In the 2005 vote, the Brotherhood ran candidates as "independents" to skirt the ban on its activities and did not field candidates in all areas.
Even when banned, the Brotherhood, founded in 1928, spent decades building up its grassroots network through social work.
The FJP statement said former NDP loyalists running in the election after forming new parties had done poorly.
"Initial results highlight that the public has sidelined the remnants of the NDP who have contested the election through parties established after the revolution," it said.
Many liberal groups, such as big parties in the Egyptian Bloc, and Islamist groups like Nour have been set up in the nine months since Mubarak's overthrow and have had to race to build a national network of supporters to campaign for them. (Additional reporting by Tom Pfeiffer and Maha El Dahan in Cairo; Writing by Edmund Blair; Editing by Peter Graff)