By Kevin Liffey
CAIRO (Reuters) - A judicial panel set up by Egypt's military-backed government supported a legal challenge to the status of the Muslim Brotherhood on Monday, compounding a drive to crush the movement behind the elected president deposed by the army in July.
While short of a formal ban on the Brotherhood, which worked underground for decades under Egypt's previous military-backed rulers, the panel's advice to a court to remove its non-governmental organization status threatens the million-member movement's future in politics.
An attack on a police station in central Cairo and plans for new mass protests by the Brotherhood on Tuesday showed the stability the interim government says it took over to impose after two-and-a-half years of turmoil is still elusive.
At least 900 people, most of them Islamist supporters of ousted President Mohamed Mursi, have been killed since the army takeover on July 3. The government has accused the Brotherhood of inciting violence and terrorism, and arrested its leaders.
Egypt's oldest political organization, the Brotherhood won a series of elections after protesters forced out longtime ruler Hosni Mubarak in 2011, culminating in last year's presidential vote. It formally registered itself in March as an NGO to secure its legal status.
The judicial panel backed Brotherhood opponents who argued that the NGO registration was illegal because the Brotherhood-led government had effectively issued a license to itself.
The panel's recommendation to the court due to rule on the case is not binding, judicial sources said, adding that the court's next session would be on November 12.
It adds to a whole array of steps taken against the Brotherhood since the army stepped in after mass protests against economic mismanagement and attempts to entrench the movement's power during Mursi's rule.
The Brotherhood formally operates in the political arena as the Freedom and Justice Party. There has so far been no attempt to outlaw the party, but its NGO status was seen as a bulwark against legal attack.
Most of the group's top leaders have been arrested and face charges of inciting violence or murder. Mursi was himself referred to trial on Sunday on those charges.
Authorities arrested on Monday one of the few remaining senior Brotherhood members who had thus far managed to evade arrest, the state news agency reported.
MENA quoted unnamed security officials as saying police had arrested Saad Husseini, who had served as governor of the Nile Delta province of Kafr el-Sheikh under Mursi, at an apartment in a Cairo suburb.
The government is shaping a new constitution to remove the Islamist additions that the Brotherhood introduced.
On Sunday it tasked a 50-member constituent assembly, which includes only two Islamists, with reviewing a draft constitution that may allow members of Mubarak's government, banned from office after the 2011 revolution, to return.
The Brotherhood accuses the "putschist regime" of staging a coup against democracy and fabricating allegations of violence and terrorism to justify a drive to erase it from public life.
The National Coalition for Legitimacy, which includes the Brotherhood, called for a "million-person march" in all Egypt's squares on Tuesday under the slogan "The Coup is Terrorism". At least six people were killed during similar protests last week.
Although the Brotherhood says it is committed to peaceful resistance, fears have grown that attacks by Islamist radicals, such as those that have already hit lawless Northern Sinai, could develop into a wider insurgency.
Memories are still vivid of an Islamist insurgency in the 1990s, when bombs and shootings destabilized Egypt and ravaged tourism.
Three people on a motorcycle hurled a homemade hand grenade at a police station in a working class area of central Cairo on Monday, wounding two workers, the state news agency said.
On Sunday, an army source said three people had been arrested for firing machineguns on Saturday at a container ship passing through the Suez Canal, the global shipping artery that runs through Egyptian territory. Canal Authority sources said a rocket-propelled grenade had also been used in the attack.
As well as being vital to global trade, the canal is one of Egypt's most important sources of income.
(Additional reporting by Asma Alsharif and Shaimaa Fayed; Writing by Tom Perry; Editing by Mohammad Zargham)