A Turkish protester holds up a banner with pictures of Turkish Prime Minister Recep Tayyip Erdogan and Turkish cleric Fethullah Gulen during a demonstration against the government on Dec. 30, 2013 in Istanbul. Ozan Kose/AFP/Getty Images

Turkey's parliament has voted to close private preparatory schools, many of which are a source of income and influence for an Islamic cleric accused by Prime Minister Recep Tayyip Erdogan of covertly seeking to topple him.

The move is the latest as Erdogan battles months of protests calling for his ouster over charges that his government is corrupt and ineffective.

Lawmakers late on Friday set a deadline of Sept. 1, 2015 to shut the schools, Turkish news channels reported. Millions of students prepare at the centers for entrance examinations to win limited spots at state high schools and universities.

The row between Erdogan and his former ally, cleric Fethullah Gulen, erupted in November when government first floated the idea of shutting down the schools, a major source of income for Gulen's Hizmet movement.

In December, a corruption scandal led to dozens of Erdogan's allies being detained in police raids on allegations of bribery in construction projects, gold smuggling and illicit dealings with Iran.

Erdogan accused so-called Gulenists implanted in Turkey's police and judiciary of being behind the graft probe in a bid to undermine his government.

"Pull your kids out, if they go to these schools. State schools are enough," Erdogan told a campaign rally in the western town of Denizli on Saturday.

"They have sucked like leeches. Leeches are more virtuous: leeches suck dirty blood, while they suck clean blood and hold sessions cursing me, my wife, my children, my administration."

The local election next month is seen as a critical test of support for Erdogan after 11 years in power.

Last week, audio recordings purportedly of Erdogan and his son Bilal discussing moving large sums of money and accepting bribes were leaked on the Internet.

Erdogan has said the audio was manipulated, and on Saturday suggested Gulen was behind the "conspiracy".

"Listening to my phone is forbidden. They listened to me, the president, my family," Erdogan said at the rally. "Now they've been caught. We are going into their lairs. It will take time but we will begin a new era with the votes we win on March 30."

Despite Erdrogan’s best efforts to appease his constituents, protests have continued for several weeks in Ankara and Istanbul. On Saturday, police used tear gas to disperse anti-government protesters.

Riot police chased dozens of protesters in a residential area near Istanbul's Taksim Square. Undercover police grabbed some of them, handcuffed them and took pictures of them.

Followers of Gulen, who preaches respect for science, democracy and dialogue with other faiths, have forged a powerful socio-religious community network.

Gulen, who lives in self-imposed exile in Pennsylvania, says he has no plans to form a political party and denies any involvement in the graft investigation.

Erdogan, a devout Muslim whose AK Party traces its roots to political Islam, remains Turkey's most popular politician.

In parliament he faces a weak opposition and, supporters argue, at the polling stations his success in driving the economy could eclipse any damage from corruption accusations.

Erdogan has said abolishing the schools is part of a larger reform of an "unhealthy" educational system that ranks Turkey below the Organization for Economic Cooperation and Development average in literacy, math and science.

Al Jazeera and wire services