Organizers of a Feb. 4 opposition march have rejected alternative routes proposed by City Hall and expressed worries that the mayor will take a tougher stance on demonstrations following the dismissal of the official responsible for approving rallies.

The opposition had wanted to march to the Kremlin walls, but City Hall rejected the petition last week and suggested routes outside the city center or moving the date of the march to Feb. 5.

"Our position for now is the following: The routes proposed by City Hall are unacceptable for us," Sergei Udaltsov, Left Front leader and co-organizer of the march, said Wednesday.

The organizers "may decide on further steps tomorrow," he told Interfax.

Organizers discussed alternative routes with Deputy Mayor Alexander Gorbenko on Tuesday but failed to reach an agreement, Interfax said.

Meanwhile, Mayor Sergei Sobyanin on Tuesday replaced the head of City Hall's security department, Valery Kadatsky, with mayoral aide Alexei Mayorov in what Udaltsov linked to a "toughening of the tactics of the federal and city authorities toward opposition and civil activists amid the growth in protest mood."

Udaltsov said he feared that "the situation might spin out of control" if organizers fail to agree on the route of the march with City Hall.

The organizers had requested permission to march from the Oktyabrskaya metro station along the Garden Ring to Manezh Square, but City Hall refused, citing concerns about security and traffic disruption, and proposed a march along Ulitsa Luzhniki and a rally at Luzhniki Stadium or Frunzenskaya Naberezhnaya.