CAIRO (Reuters) - Egypt detained a leading opposition figure and allies on Tuesday on charges of plotting to bring down the government, but opposition groups said the arrests aimed to stymie their preparations for parliamentary elections next year.

Zyad Elelaimy, a prominent member of the Social Democratic Party and the Civil Democratic Movement, was held along with at least seven others, the interior ministry said in a statement.

Elelaimy, who was also a leading member of the 2011 protests that unseated long time ruler Hosni Mubarak, was arrested minutes after leaving a friend’s house in Cairo’s Maadi district around 2:20 a.m., eyewitnesses said.

“About two minutes after he left we heard him calling us. We looked from our balcony and we saw him being pushed into a civilian car by a large number of people in civilian clothes,” a friend, Soha Bayoumi, told Reuters.

“It seems that they were waiting for him, it was an ambush,” Bayoumi added, saying that the people who arrested Elelaimy identified themselves as national security agents.

The interior ministry accused Elelaimy and seven others of involvement in a plan fomented and financed through Muslim Brotherhood leaders abroad “to carry out violent and disorderly acts against state institutions simultaneously with creating a state of revolutionary momentum.”

The Civil Democratic Movement (CDM), a coalition of Egyptian opposition parties and figures, denied Elelaimy and the others arrested had any connections with the Muslim Brotherhood, which was banned and declared a terrorist organization in Egypt in 2013.

One of Elelaimy’s colleagues said he believed the arrest was linked to the coalition’s move to seek more members to prepare for parliamentary elections next year.

“We have nothing to do with the Brotherhood ... I am truly astonished and I don’t know why security would be upset that we want to take part in the elections in the framework of the law and constitution,” said CDM member Khaled Dawoud, adding that the group has had only one meeting and was planning for another soon.

Human rights lawyer Gamal Eid, who is representing some of the defendants, said at least 10 people were arrested in recent days and were being questioned at state security prosecution headquarters on Tuesday.

Eid said the charges include financing a terrorist organization and publishing false news. Eid said the case is “fabricated” and aims at “spreading fear” among the opposition ahead of the anniversary of the June 30, 2013 uprising that toppled President Mohamed Mursi of the Muslim Brotherhood.

Last week, Mursi suffered a fatal heart attack in court at a Cairo prison, authorities said. The Muslim Brotherhood described Mursi’s death as “full-fledged murder.”

Opposition figures and activists Hisham Foad, Hossam Moeness, Omar el-Shenety, Ahmed el-Akabawy and Hassan al-Barbarry were among those who had been arrested in recent days.

Since becoming president in 2014, former army chief President Abdel Fattah al-Sisi has overseen a crackdown that has swept up Islamists and liberal opponents.

At least 60,000 people have been jailed, according to Human Rights Watch. Sisi has denied holding political prisoners and his backers say the measures were necessary to stabilize Egypt.

“They regularly arrest people to scare anyone else who consider challenging them, even according to the highly restrictive rules they’ve set as through the parliament,” said Timothy Kaldas, non-resident fellow at the Tahrir Institute for Middle East Policy.

“They want to destroy any hope in the public that they have a place in Egypt’s political life,” Kaldas said.