* Special courts convicted more than 200 in Ergenekon case
* Abolition seen as part of battle for judiciary
* Comes after graft probe Erdogan called "dirty plot"
By Humeyra Pamuk
ANKARA, Jan 29 (Reuters) - The Turkish government plans to abolish special courts which tried alleged coup plotters, it said on Wednesday, a move seen as part of the ruling AK Party's efforts to counter forces hostile to it in the judiciary.
Closing the courts that have convicted hundreds of army officers and others in recent years may also be aimed at winning Prime Minister Tayyip Erdogan support from secularists as he fends off what he calls "a dirty plot" by former allies, judicial observers say.
"We will be taking a historical step that we should already have taken, as a state of law," Justice Minister Bekir Bozdag told reporters.
"There will no longer be different criminal courts within the judiciary and different methods of investigation."
The government has removed thousands of police chiefs and more than a hundred prosecutors since a corruption investigation in December that led to three cabinet resignations and which Erdogan called an attempted coup by a "parallel state".
That was a veiled reference to supporters of U.S.-based Turkish cleric Fethullah Gulen who exerts strong if covert influence in the police and judiciary.
The abolition of the special courts could mean some cases in which military officers and others were convicted of plotting coups against the government of Erdogan's Islamist-roooted party - including the 2013 Ergenekon case - could be retried in regular criminal courts.
Bozdag confirmed that his ministry was looking into possible retrials of those cases.
Some analysts say that could be a way for Erdogan to gain support from more secular parts of the establishment as he deals with the perceived threat from Gulen, a former ally.
The head of Turkey's Association of Judges and Prosecutors (YARSAV) said the Special Authority Courts should have been abolished long ago due to their "anti-democratic nature".
"The AK party used these courts as a tool to redesign politics," YARSAV's Murat Arslan told Reuters
"Now they are seeking to form new alliances and the people that have been harmed by the Cemaat (Gulen's movement) could be the support it is looking for," Arslan said.
Erdogan's AK Party is believed to have relied heavily on Gulen's influence in breaking the power of an army that carried out three coups between 1960 and 1980 and forced an Islamist-led government from power in 1997. (Editing by Daren Butler and Robin Pomeroy)