Egypt's army-backed authorities arrested the spokesman of the Muslim Brotherhood on Tuesday and froze the assets of other Islamists, in a new blow to deposed president Mohamed Morsi's supporters.
Since Morsi's overthrow by the army on July 3 and his detention, more than 2,000 members of the Brotherhood have been arrested and several are facing trial.
The crackdown that has fractured the Brotherhood's organisation has also seen hundreds of Islamist supporters killed in clashes across the country.
In a new blow to the Brotherhood, police arrested group spokesman Gehad al-Haddad and five others on Tuesday.
An arrest warrant had been outstanding for Haddad, who was active on social networks. For weeks he managed to escape arrest although he kept active on social networks and appeared frequently on television.
Among the others arrested Tuesday was a Morsi-appointed former provincial governor, Hossam Abu Bakr, in an apartment in Cairo's Nasr City district, security sources said.
The six men are to be held at Cairo's Tora prison where several top Brotherhood figures are jailed, including the group's supreme guide Mohamed Badie, security sources said.
Nasr City was the epicentre of pro-Morsi protests, where the deposed president's supporters camped for weeks to demand his reinstatement and clashed with security forces.
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Morsi has been held at a undisclosed location since his overthrow in a military-led coup following massive protests against his one-year turbulent rule.
In mid-August the military-backed interim government launched a bloody operation to break up two pro-Morsi protest camps in Cairo, including in Nasr City. Hundreds of people there, and elsewhere in the country, were killed in ensuing clashes.
By the following week, more than 1,000 people had been killed in violence across Egypt, most of them Morsi supporters.
Haddad's arrest came as an Egyptian court ordered the freezing of the assets of top Brotherhood chief Badie, his two deputies Khairat al-Shater and Rashad Bayoumi, as well as Salafist leader Hazem Abu Ismail and preacher Safwat Higazi.
The five are currently under arrest, accused of inciting the murder of protesters opposed to Morsi.
Around 15 Islamist politicians have already had their assets frozen as part of the crackdown against the Brotherhood, a once formidable and highly organised movement founded in Egypt in 1928.
Long banned in Egypt, the group had become gradually more tolerated in the years before the 2011 revolution, winning parliamentary seats through candidates who ran as independents.
It took centre-stage only after the uprising which toppled president Hosni Mubarak, winning a majority in parliament and then the presidency. But Morsi's July 3 ouster has reset the clock.
The violent dispersal of the protest camps in August and the campaign of arrests has thinned Brotherhood ranks and made it increasingly difficult for it to mobilise large numbers of supporters.
The new authorities have laid out a political roadmap which provides for parliamentary and presidential elections in 2014.