Cairo: Reeling from a humiliating rout in Egypt's legislative elections, the Muslim Brotherhood, the nation's strongest opposition force despite a ban, said on Tuesday it would pursue a "local and international" legal battle against the Egyptian government to expose alleged vote fraud.

"We will not quit the run-off vote [next Sunday]. However, we will continue to collect all documents substantiated with figures to use them in the local and international legal pursuit," Mohammad Badaei, the Supreme Guide of the Islamist group told a press conference in Cairo on Tuesday.

None of the 130 candidates fielded as independents by the group won a parliamentary seat, but the group still has 25 candidates contesting next Sunday's run-off vote.

The Muslim Brotherhood, officially banned since 1954 in Egypt, garnered a fifth of the parliament's seats in 2005.

"We will never relent or allow corruption to prevail in this country," added Badaei. Though voices are being raised inside the group to quit the run-off, Badaei said: "Our duty is to expose injustice and face up to it, whatever sacrifices are." He reiterated that the group would "tread on our peaceful path".

The group was the target of a massive security crackdown in the run-up to the latest elections, with its lawyers saying more than 1,000 of its members detained.

"What happened on Sunday was catastrophic. According to our survey, polling stations in which vote rigging took place had a 97 per cent turnout," Sa'ad Al Katatni, head of the group's bloc in the outgoing parliament, told a news conference.

Al Katatni too lost the seat he won in 2005 with a hefty majority of votes.

Voter turnout was officially put at 25 per cent but rights groups who sent monitors to polling stations said it was only half that figure.