CAIRO - Supporters of Egypt’s deposed president Mohamed Morsi vowed more rallies and called for marches on Friday as police arrested another senior Islamist in an ongoing crackdown on Morsi loyalists.

The call for further protests came as the interior ministry announced the arrest on Thursday of Muslim Brotherhood politician, Mohamed al-Beltagi in a village outside Cairo.

Elsewhere in Egypt, police arrested 28 Islamists, the official MENA news agency reported.

After arresting much of the movement’s leadership, the police have begun rounding up mid-level operatives around the country.

The interior ministry also warned Thursday that live ammunition will be used on protesters who attack public institutions.

Decapitated and harried by the police crackdown, the Islamist movement pressing for Morsi’s reinstatement has only been able to muster several thousand protesters in recent rallies.

“We welcome any calls for calm, but we will continue protesting in a peaceful manner,” Salah Gomaa, a member of the Anti-Coup Alliance led by Morsi’s Muslim Brotherhood, told a news conference.

The Islamist coalition has held almost daily rallies following a deadly police operation on August 14 to disperse their two protest camps in Cairo.

More than 1,000 people were killed in the operation and ensuing violence, and police have rounded up more than 2,000 Islamists, according to security sources.

On Thursday, the interior ministry said police arrested Beltagi, a firebrand politician, along with Khaled al-Azhari, a former Islamist cabinet minister in Morsi’s government.

A former member of parliament, Beltagi became one of the most vociferous opponents of the popularly backed military coup that toppled the Islamist Morsi on July 3.

Prosecutors had issued a warrant for Beltagi on charges of inciting violence.

Although he possessed little influence in the Brotherhood’s top ranks, his fiery stump speeches had created a following among Islamist youths.

He had appeared in a recent video recorded in hiding to urge mass rallies to reinstate Morsi, whom the military overthrew in a July 3 popularly backed coup.

The interior ministry said in a statement that it would forcefully confront any “attempt to affect the stability of public security.”

“In light of calls by wanted leaders of the Muslim Brotherhood for protests on Friday June 30... the interior ministry affirms its forces’ readiness to confront any violation of the law,” it said.

In a statement, the Anti-Coup Alliance called for the release of prisoners and demanded a probe into the violence over the past month.

Police have already arrested the Brotherhood’s supreme guide Mohamed Badie and much of the senior leadership.

Badie and his deputies are standing trial on charges of involvement in the murder of protesters who stormed the Brotherhood’s headquarters on June 30.

Morsi himself is being held at a secret location and faces charges related to his 2011 escape from prison and of inciting the death and torture of protesters.

The crackdown on the Islamists has severely impacted their ability to gather supporters on the street. Last Friday, only several thousand people heeded their call for marches in Cairo.