Vast crowds of students surged onto Istanbul’s streets in the latest protest over the arrest and jailing of Istanbul’s opposition mayor that has sparked Turkey’s worst unrest in years.

The demonstrations began after Ekrem Imamoglu’s March 19 arrest and have since spread to at least 55 of Turkey’s 81 provinces, sparking clashes with riot police and drawing international condemnation.

Police have arrested more than 1,130 people over the past six days, including 43 on Monday night, the interior minister said. Among them are journalists.

9News Nigeria reports that Imamoglu, 53, of the opposition CHP party, is widely seen as the only politician capable of defeating Turkey’s longtime leader Erdogan at the ballot box.

In just four days he went from being the mayor of Istanbul — a post that launched Erdogan’s political rise decades earlier — to being arrested, interrogated, jailed and stripped of the mayorship as a result of a graft and terror probe.

Students in both Istanbul and the capital Ankara began gathering in the early afternoon after announcing they were boycotting lectures at the main universities in both cities.

In Istanbul, as crowds of chanting, flag-waving students headed through the streets to Besiktas, a port on the Bosphorus, residents applauded and banged saucepans in a show of support.