Associated Press has reported the searching of several opposition leaders’ homes today by Russian authorities, who have also called the leaders in for questioning. This move is seen to have raised tensions ahead of a large scale protest against Vladimir Putin, planned for tomorrow.

AP reports that “some opposition activists predict the crackdown will fuel anger and bring out more people for Tuesday’s protest. Others worry that it will frighten away the middle-class and young white-collar professionals whose new political activism has posed the first serious challenge to Putin since he came to power in 2000.”

Among those reported to have been searched today are Alexey Navalny, Sergei Udaltsov and Ilya Yashin.

“All of the opposition leaders subject to searches had been summoned for questioning on June 12, a national holiday, making it difficult if not impossible for them to attend the protest that begins at noon” AP reports.

The Russian investigators suggested the searches related to the latest large scale protest on May 6th, where conflict arose between police and protesters.

Read the full story on Associated Press.