CAIRO (REUTERS) - An Egyptian judge sentenced 185 Muslim Brotherhood supporters to death on Tuesday over an attack on a police station near Cairo last year in which 12 policemen were killed.

The ruling is preliminary and subject to a lengthy appeals process. It also goes to the country's top religious authority for approval although his opinion is not binding.

The sentence comes days after another court dropped charges against Hosni Mubarak over the killing of protesters during the 2011 uprising that ended his 30-year rule.

The attack on the Kerdasa police station took place on Aug 14, 2013, the day that Egyptian security forces cleared two Brotherhood protest camps in Cairo, killing hundreds of people in one of the bloodiest episodes in Egypt's modern history.

Of those sentenced, 151 are in custody, with the others being tried in absentia, a judicial source said.

Egyptian authorities have rounded up thousands of Brotherhood members since the army ousted Islamist President Mohamed Morsi in July last year, following protests against his turbulent one-year rule.

Egyptian courts have since sentenced hundreds to death in mass trials that have been condemned by human rights groups.

Abdel Fattah al-Sisi, the army chief who orchestrated Mursi's removal, went on to win a presidential election in May.

His critics say he has steadily rolled back the freedoms won in the 2011 uprising, but many Egyptians appear willing to tolerate those curbs, seeing them as the price to pay to restore stability and economic growth.

None of those sentenced since Morsi's ouster have been executed so far.