Tarek Bedair, an Al-Gamaa Al-Islamiya leader in Assiut, said that the ultra-conservative group had deployed its younger members in an attempt to maintain security in the city, where some police officers are on strike.
"Al-Gamaa Al-Islamiya is not seeking to replace the police, but rather to fill a security vacuum [in the city]," Bedair said in a telephone interview with Al-Hayat satellite TV channel on Tuesday evening.
The channel earlier broadcast a video depicting a parade of motorbikes and cars that it described as the "Al-Gamaa Al-Islamiya police" patrolling the city's streets.
The Islamist group had announced on Friday it planned to use its 'popular committees' to protect Assiut if Egyptian police failed to return to work. Many condemned the announcement fearing it might prompt political groups to start establishing militias.
Bedair said that his group had contributed to handling a number of crises in the city resulting from negligence on the part of regional government officials, including distributing food, butane gas for cooking, and fuel, as well as rubbish collection.
Bedair described the move as driven by "a sense of responsibility and an attempt to ensure the stability of the state."
However, Assiut Security Chief Major General Abul Kassem Abu Deif rejected moves by any political group to create bodies parallel to the state's security apparatus.
"Maintaining security and protecting the citizenry is the responsibility of the police and what Al-Gamaa Al-Islamiya has done is illegal," he told the channel.
Chief security officer in Upper Egypt's Minya, Ahmed Soliman, also dismissed the Islamist group's initiative, saying that police stations in Minya merely closed for a few hours and then went back to normal business, after meeting with striking officers and forwarding their demands to the interior minister.
Meanwhile, police officers in the security directorate of the Daqahliya governorate, north east of Cairo, and in Mansoura in the Delta, have called off the strike action they began eight days ago.
Police officers and low-ranking personnel in North Sinai's Arish are taking part in a partial strike for the second day in a row, with some refusing to deploy to security service sites.
Last week, discontent within the ranks of Egypt's police led to a strike at police stations in over a third of Egyptian governorates.
On Monday, an interior ministry source told Ahram Arabic news website that police strikes are diminishing, covering no more than at most one percent of the total number of police stations countrywide.